When a child is declared a dependent of the court (Welf. & Inst. Code, § 300)1 and is removed from parental custody, the trial court must generally order the department of social services to provide reunification services to the parent, and the court must schedule a review hearing in six months.
Ordinarily, the department of social services must provide the parent with reunification services for one year. (§ 361.5, subd. (a)(1); Cal. Rules of Court, rule 1456(f)(1).) But at the six-month review hearing the trial court may terminate reunification services and schedule a permanency planning hearing that may forever deprive the parent of any parental rights “[i]f the child was removed initially under subdivision (g) of Section 300 and the court finds by clear and convincing evidence that the whereabouts of the parent are still unknown, or the parent has failed to contact and visit the child . . . .” (§ 366.21, subd. (e), italics added.) At issue here is this: Does the italicized phrase apply only when the child has been removed under subdivision (g) of section 300? According to the majority, the answer is “no.” I disagree.
I
In 2003, the Tuolumne County Department of Social Services (Department) filed a dependency petition alleging that the three children of Sara M. should be declared dependents under subdivisions (b) (failure to protect) and (c) (serious emotional damage) of section 300 because Sara was a drug addict who was not providing them with adequate food, clothing, and shelter. The trial court sustained the petition, ordered the Department to provide Sara with reunification services (including visitation), and scheduled a six-month review hearing for June 13, 2004. Sara’s case worker told her that she had one year to complete the reunification plan, and that if she failed to do so the court would order a permanent plan that could result in termination of her parental rights. A court order and a letter to Sara from a social worker also said that she had one year to comply with the reunification plan.
Sara did not comply with the reunification program during the first six months of the dependency. She visited the children once at the beginning of *1020the dependency, but the visit did not go well. She tried to visit a second time shortly before the six-month review hearing, but she was not allowed to see the children after she admitted being under the influence of methamphetamine and marijuana; she was told that she could see the children only if she stopped using drugs. At the six-month review on June 22, 2004, the trial court told Sara it would terminate reunification services if she did not make a greater effort to comply with the reunification program; the court continued the matter for three weeks to check on Sara’s progress.
Later that day, Sara drove to her social worker’s office and submitted to a drug test; when the test was positive for methamphetamine, the social worker had Sara arrested for driving under the influence. The next week the police arrested her for possession of a controlled substance and drug paraphernalia, both misdemeanors. At the progress hearing, the trial court ordered termination of reunification services and scheduled a permanency planning hearing. Sara filed a writ petition challenging these rulings. The Court of Appeal held that the trial court’s orders were premature. It directed the trial court to vacate the permanency planning hearing and to reinstate reunification services for an additional six months.
II
A child may be made a dependent of the court for many reasons, as set forth in section 300’s 10 subdivisions. Subdivisions (b) and (c), under which the dependency in this case was created, authorize a dependency when a parent has willfully or negligently failed to protect the child from abuse or to provide adequate food, clothing, and shelter (subd. (b)) and when the child has suffered or is at risk of suffering serious emotional damage (subd. (c)). Also pertinent here is subdivision (g), which authorizes a dependency when a child is left without support; when a parent voluntarily surrenders custody of a child and thereafter does not reclaim it; when a parent is incarcerated or institutionalized and cannot arrange for the child’s care; and when a custodian with whom the child is living cannot or will not care for the child, the parent’s whereabouts are unknown, and reasonable efforts to locate the parent are unsuccessful. Other subdivisions of section 300 authorize dependencies for physical abuse (subd. (a)), sexual abuse (subd. (d)), abuse inflicted on a young child by another person with the parent’s knowledge (subd. (e)), negligently or intentionally causing the death of another child (subd. (f)), relinquishment for adoption (subd. (h)), acts of cruelty (subd. (i)), and abuse or neglect of a sibling (subd. (j)).
Once a dependency is created, the trial court must, subject to certain exceptions, provide the parents with reunification services and must schedule a review hearing in six months.
*1021Subdivision (e) of section 366.21 (section 366.21(e)), at issue here, contains eight paragraphs, all of which pertain to the six-month review hearing. It explains that at the review hearing the trial court must return the child to the parent’s custody unless it finds that doing so would be detrimental to the child, that the court must make findings justifying a continued detention of the child, and that the court must warn the parent that if return of the child is still inappropriate after an additional six months, a permanency planning hearing may be scheduled.
As a general rule, after the six-month review hearing the parent must be provided with reunification services for an additional six months. But section 366.21(e) provides that in certain circumstances, which are described in four paragraphs, the court may terminate reunification services at the review hearing. Pertinent here is one of these paragraphs, the fifth paragraph of section 366.21(e), which states: “If the child was removed initially under subdivision (g) of Section 300 and the court finds by clear and convincing evidence the whereabouts of the parent are still unknown, or the parent has failed to contact and visit the child, the court may schedule a [permanency planning] hearing . . . within 120 days. If the court finds by clear and convincing evidence that the parent has been convicted of a felony indicating parental unfitness, the court may schedule a [permanency planning] hearing . . . within 120 days.” (Italics added.)
At issue here is whether, as the Court of Appeal concluded, the italicized phrase applies only when the dependency was created under subdivision (g) of section 300, or whether, as the majority concludes, the italicized phrase applies to dependencies created under any subdivision of section 300. To answer that question, I turn to our standard rules of statutory construction. “The objective of statutory construction is to determine the intent of the enacting body so that the law may receive the interpretation that best effectuates that intent. (Hassan v. Mercy American River Hospital (2003) 31 Cal.4th 709, 715 [3 Cal.Rptr.3d 623, 74 P.3d 726].) ‘We first examine the words themselves because the statutory language is generally the most reliable indicator of legislative intent. [Citation.] The words of the statute should be given their ordinary and usual meaning and should be construed in their statutory context.’ (Ibid.) If the plain, commonsense meaning of a statute’s words is unambiguous, the plain meaning controls. (In re Jennings (2004) 34 Cal.4th 254, 263 [17 Cal.Rptr.3d 645, 95 P.3d 906].)” (Fitch v. Select Products Company (2005) 36 Cal.4th 812, 818 [31 Cal.Rptr.3d 591, 115 P.3d 1233].)
The majority construes the fifth paragraph of section 366.21(e) as permitting the trial court to set the matter for a permanency planning hearing in three circumstances: (1) “If the child was removed initially under subdivision (g) of Section 300 and the court finds by clear and convincing evidence that *1022the whereabouts of the parent are still unknown,” (2) “[i]f ... the parent has failed to contact and visit the child,” and (3) “[i]f the court finds by clear and convincing evidence that the parent has been convicted of a felony indicating parental unfitness.” (§ 366.21(e).) So construed, there is a standard of proof (clear and convincing evidence) that the Legislature specified for the first and third of these circumstances, but not for the second. The majority offers no explanation for that legislative omission.
The Court of Appeal, by contrast, concluded that the phrase at issue in the fifth paragraph of section 366.21(e), which I italicized in my discussion at page 1009, ante, refers back to the beginning of the sentence, which states, “If the child was removed initially under subdivision (g) of Section 300 Therefore, the Court of Appeal said, the italicized phrase applies only when the child was initially made a dependent under subdivision (g) of section 300. Under that interpretation, a trial court can schedule a permanency planning hearing at the time of the six-month review in two circumstances. The first has two subgroups: “If the child was removed initially under subdivision (g) of Section 300 and the court finds by clear and convincing evidence [either (a)] the whereabouts of the parent are still unknown, or [(b)] the parent has failed to contact and visit the child.” (§ 366.21(e).) The second circumstance occurs “[i]f the court finds by clear and convincing evidence that the parent has been convicted of a felony indicating parental unfitness.” (Ibid.) Under the Court of Appeal’s interpretation, the Legislature specified a standard of proof (clear and convincing evidence) for each of the categories listed in the paragraph at issue, whereas the majority’s construction here leaves one of the categories without a standard of proof.
Furthermore, the second of the majority’s three categories (“[i]f ... the parent has failed to contact and visit the child”) is so all-encompassing that it completely swallows up the first category (“[i]f the child was removed initially under subdivision (g) of Section 300 and the court finds by clear and convincing evidence that the whereabouts of the parent are still unknown”), leaving the first category meaningless. Otherwise stated, if the child was initially removed because the parent’s whereabouts were unknown, and the parent’s whereabouts are still unknown at the trial court’s six-month review, it is unlikely that the parent would have contacted or visited the child during the intervening time.
Thus, the majority’s interpretation of the fifth paragraph of section 366.21(e) turns the entire first clause of the paragraph (“If the child was removed initially under subdivision (g) of Section 300 and the court finds by clear and convincing evidence that the whereabouts of the parent are still unknown”) into mere surplusage. This violates “one of the guiding principles of statutory construction, that significance be accorded every word of an act.” *1023(People v. Johnson (2002) 28 Cal.4th 240, 246-247 [121 Cal.Rptr.2d 197, 47 P.3d 1064].) This court has repeatedly explained that ‘.‘whenever possible, significance must be given to every word in pursuing the legislative purpose, and the court should avoid a construction that makes some words surplus-age.” (Agnew v. State Bd. of Equalization (1999) 21 Cal.4th 310, 330 [87 Cal.Rptr.2d 423, 981 P.2d 52]; see also Elsner v. Uveges (2004) 34 Cal.4th 915, 931 [22 Cal.Rptr.3d 530, 102 P.3d 915]; Arnett v. Dal Cielo (1996) 14 Cal.4th 4, 22 [56 Cal.Rptr.2d 706, 923 P.2d 1]; Williams v. Superior Court (1993) 5 Cal.4th 337, 357 [19 Cal.Rptr.2d 882, 852 P.2d 377]; Brown v. Superior Court (1984) 37 Cal.3d 477, 484 [208 Cal.Rptr. 724, 691 P.2d 272]; City and County of San Francisco v. Farrell (1982) 32 Cal.3d 47, 54 [184 Cal.Rptr. 713, 648 P.2d 935].)
Under the Court of Appeal’s statutory interpretation, by contrast, there is no surplusage. In essence, the Court of Appeal construed the first sentence of the fifth paragraph of section 366.21(e) as saying that a trial court may schedule a permanency planning hearing at the six-month review hearing if the child was removed because the parent abandoned the child and either (1) the parent’s whereabouts are still unknown at the time of the review hearing, or (2) even though the parent’s whereabouts have been discovered, the parent has not visited the child. These categories do not overlap, and neither is so broad that it encompasses the other.
As previously mentioned, the statutory scheme generally provides for up to one year of services designed to reunify the parent and child before a permanency planning hearing is scheduled. (§ 361.5, subd. (a)(1); Cal. Rules of Court, rule 1456(f)(1); see generally, Cynthia D. v. Superior Court (1993) 5 Cal.4th 242, 248-249 [19 Cal.Rptr.2d 698, 851 P.2d 1307].) Under the majority’s interpretation of the fifth paragraph of section 366.21, a trial court may end reunification services after only six months even when, as in this case, a parent whose child was removed for reasons unrelated to abandonment has shown an interest in visiting the child, but has not been permitted to do so because of a continuing substance abuse problem. This broad reading is inconsistent with the statutory scheme’s general policy of giving a parent a year to meet the requirements of an individualized reunification plan. As interpreted by the Court of Appeal, however, the Legislature crafted a narrow exception to that general policy when a parent who initially abandoned the child has shown no interest in reunification (because the parent’s whereabouts are unknown or the parent has not visited the child), or when a parent has been convicted of a felony that demonstrates parental unfitness. Offering an additional six months of services to such parents would be pointless, because further services would not redress the problems that resulted in the dependency. (See Carolyn R. v. Superior Court (1995) 41 Cal.App.4th 159, 166 [48 Cal.Rptr.2d 669] [goal of reunification services is to “address the circumstances which required . . . court intervention into a family’s life”].)
*1024In short, the majority’s interpretation of the fifth paragraph of section 366.21(e) makes one clause of the paragraph meaningless, is based on the assumption that the Legislature specified a standard of proof for two of the categories of cases discussed in the paragraph but not the third, and is inconsistent with the statutory scheme governing dependencies. By contrast, the Court of Appeal’s statutory interpretation gives meaning to all of the words in the paragraph at issue, it specifies a standard of proof for each of the categories of cases discussed in the paragraph, and it is consistent with the statutory scheme. That construction far better reflects the Legislature’s intent than that of the majority here.
Ill
The majority’s construction of the fifth paragraph of section 366.21(e) mirrors that of the Judicial Council, as reflected in rule 1460(f)(1) of the California Rules of Court. After considerable discussion of Yamaha Corp. of America v. State Bd. of Equalization (1998) 19 Cal.4th 1 [78 Cal.Rptr.2d 1, 960 P.2d 1031] (Yamaha), in which this court described the circumstances in which it defers to the statutory interpretations of administrative agencies, the majority concludes that the Judicial Council’s interpretation, in rule 1460(f)(1), of the fifth paragraph of section 366.21(e) “is entitled to great weight and will be overturned only if it is clearly erroneous.” (Maj. opn., ante, at p. 1014.) Applying that standard, the majority concludes that it “will not overturn” the Judicial Council’s interpretation. (Maj. opn., ante, at p. 1005.)
Yamaha relied heavily on Professor Michael Asimow’s views on administrative law, as expressed in a law review article (Asimow, The Scope of Judicial Review of Decisions of California Administrative Agencies (1995) 42 UCLA L.Rev. 1157 (Asimow)) and reflected in his work as administrative law adviser to the California Law Revision Commission (Cal. Law Revision Com., Tent. Recommendation: Judicial Review of Agency Action (Aug. 1995)). As pertinent here, Professor Asimow explained that in considering whether to defer to an administrative agency’s determination on a question of law, courts look at certain factors to decide whether an administrative agency has a “comparative interpretive advantage over courts” (Asimow, supra, 42 UCLA L.Rev. at p. 1195; see also Yamaha, supra, 19 Cal.4th at p. 12), and the courts also look at other factors to determine whether the administrative agency’s interpretation has been carefully considered and consistently maintained (Asimow, supra, 42 UCLA L.Rev. at pp. 1196-1198; Yamaha, supra, 19 Cal.4th at p. 13). As the majority here observes, the second group of factors tend to suggest deference to the Judicial Council’s interpretation of the fifth paragraph of section 366.21(e). (Maj. opn., ante, at pp. 1013-1014.) *1025But the majority does not discuss the first group of factors, which I outline below and which point in the opposite direction.
In the words of Professor Asimow: “[A]gencies are often immersed in administering a particular statute. Such specialization gives those agencies an intimate knowledge of the problems dealt with in the statute and the various administrative consequences arising from particular interpretations. In contrast, a generalist court that visits a particular regulatory statute only infrequently lacks the advantage arising out of specialization. . . . [I]f by reason of expertise, specialization or both, an agency demonstrably has qualifications to interpret a particular text that are superior to the court’s, deference is appropriate. [$]... A court is [also] more likely to defer to an agency’s interpretation of its own regulation than to its interpretation of a statute . . . [and is] more likely to defer to an agency’s interpretation of a statute that the agency enforces than to its interpretations of some other statute . . . .” (Asimow, supra, 42 UCLA L.Rev. at p. 1196, fin. omitted; see also Yamaha, supra, 19 Cal.4th at p. 12.)
Here, section 366.21(e) is not a “regulatory statute” that the Judicial Council is “immersed in administering.” (Asimow, supra, 42 UCLA L.Rev. at p. 1196.) Nor does an interpretation of the statute give rise to “administrative consequences.” (Ibid.) Nor is it the Judicial Council’s “own regulation,” nor is it “a statute that the [Judicial Council] enforces.” (Ibid.) Rather, section 366.21(e) is a law pertaining to judicial, not administrative, proceedings. I do not question the Judicial Council’s expertise in matters pertaining to judicial proceedings. But such matters also fall squarely within the scope of this court’s expertise. Because this court’s expertise in interpreting laws pertaining to judicial proceedings is equal to or greater than that of the Judicial Council, deference to the Judicial Council in such matters is unwarranted.
The majority points out that in Adams v. Commission on Judicial Performance (1994) 8 Cal.4th 630 [34 Cal.Rptr.2d 641, 882 P.2d 358], this court said that the Judicial Council’s interpretation of a constitutional provision, as reflected in its rules, should be “accorded considerable weight” and should not be rejected unless it is “clearly erroneous or unauthorized.” (Id. at pp. 657-658.) But there the provision in question pertained to hearings before the Commission on Judicial Performance, which are administrative proceedings. Judicial Council rules are not given deference when, as in this case, they pertain to the operation of the judicial system, because in such matters the Judicial Council’s expertise in determining the Legislature’s intent does not exceed that of the appellate courts. (See, e.g., People v. Hall (1994) 8 Cal.4th 950, 963 [35 Cal.Rptr.2d 432, 883 P.2d 974]; In re Robin M. (1978) 21 Cal.3d 337, 346 [146 Cal.Rptr. 352, 579 P.2d 1]; Polibrid Coatings, Inc. v. Superior Court (2003) 112 Cal.App.4th 920, 923 [6 Cal.Rptr.3d 7]; *1026Maribel M. v. Superior Court (1998) 61 Cal.App.4th 1469, 1476 [72 Cal.Rptr.2d 536]; Trans-Action Commercial Investors, Ltd. v. Firmaterr, Inc. (1997) 60 Cal.App.4th 352, 363-372 [70 Cal.Rptr.2d 449]; California Court Reporters Assn. v. Judicial Council of California (1996) 39 Cal.App.4th 15, 33-34 [46 Cal.Rptr.2d 44]; In re Keisha T. (1995) 38 Cal.App.4th 220, 235 [44 Cal.Rptr.2d 822]; People v. Zamarron (1994) 30 Cal.App.4th 865, 872 [36 Cal.Rptr.2d 17]; Sadler v. Turner (1986) 186 Cal.App.3d 245, 248-250 [230 Cal.Rptr. 561]; Iverson v. Superior Court (1985) 167 Cal.App.3d 544, 548 [213 Cal.Rptr. 399]; Alsavon M. v. Superior Court (1981) 124 Cal.App.3d 586, 594-595 [177 Cal.Rptr. 434].)
Thus, unlike the majority, I would not defer to the Judicial Council’s interpretation of the fifth paragraph of section 366.21(e). Even if deference would be appropriate when two competing interpretations of a statute were equally plausible, here they are not. As I have previously explained (see pt. II, ante), the majority’s interpretation of the statutory language at issue, which is reflected in California Rules of Court, rule 1460(f)(1) adopted by the Judicial Council, is inconsistent with the plain meaning of the statutory language. Therefore, I would reject that interpretation.
The majority also reasons that the principle of legislative acquiescence supports its interpretation of section 366.21(e). It points out that rule 1460(f)(1) of the California Rules of Court, whose interpretation of the fifth paragraph in section 366.21(e) the majority adopts here, was promulgated in 1990, and that three years later, the Court of Appeal in In re Monique S. (1993) 21 Cal.App.4th 677 [25 Cal.Rptr.2d 863], reached the same interpretation. Since then, the majority notes, the Legislature has often amended section :366.21, but it has left the paragraph at issue here unchanged. (Maj. opn., ante, at p. 1014.)
As this court has stressed in the past, “legislative inaction is indeed a slim reed upon which to lean.” (Quinn v. State of California (1975) 15 Cal.3d 162, 175 [124 Cal.Rptr. 1, 539 P.2d 761]; see also Harris v. Capital Growth Investors XIV (1991) 52 Cal.3d 1142, 1156 [278 Cal.Rptr. 614, 805 P.2d 873].) Section 366.21 is an exceptionally long statute that includes 39 paragraphs. In my view, the Legislature’s decision to amend portions of this complex provision is not persuasive evidence that it intended to acquiesce in court rules or decisions construing other unrelated parts, such as the paragraph at issue here. (See People v. Blakeley (2000) 23 Cal.4th 82, 90 [96 Cal.Rptr.2d 451, 999 P.2d 675]; People v. Morante (1999) 20 Cal.4th 403, 429 [84 Cal.Rptr.2d 665, 975 P.2d 1071]; People v. Escobar (1992) 3 Cal.4th 740, 751 [12 Cal.Rptr.2d 586, 837 P.2d 1100].)
*1027Conclusion
Because Sara’s three children were not made dependents under subdivision (g) of section 300, she was entitled to a year of reunification services (as mentioned in the trial court’s order and in a letter to Sara from her social worker), rather than the six months allowed by the majority, before the trial court could schedule a permanency planning hearing. Thus, the trial court erred when it terminated reunification services after only six months. For the reasons given above, I would affirm the judgment of the Court of Appeal, which reversed the trial court’s order terminating reunification services.
Moreno, J., concurred.
All further statutory citations are to the Welfare and Institutions Code.