Under Welfare and Institutions Code section 3201, subdivision (c), a convicted felon committed to the California Rehabilitation Center (CRC) for treatment because of actual or potential drug addiction may be confined for no longer than “a period of time . . . equal to that which he or she would have otherwise spent in state prison had sentence been executed, including application of good behavior and participation credit provisions of Article 2.5 (commencing with Section 2930) of Chapter 7 of Title 1 of Part 3 of the Penal Code . . . .”
In 1980, when subdivision (c) was first added to Welfare and Institutions Code section 3201, Penal Code section 2931 provided that felons sentenced to the state prison could claim, for every two days spent in custody, one day of credit for good behavior and participation in certain prison programs (hereafter good behavior and participation credits). At that time, such credits were also available to felons who, because of drug addiction, were committed to CRC. (Welf. & Inst. Code, § 3201, subd. (c).) Later, however, the Legislature amended Penal Code section 2931 to make its provisions inapplicable “to any person whose crime was committed on or after January 1, 1983.” (Stats. 1982, ch. 1234, § 2, p. 4549.) This amendment, the majority concludes, precludes post-1982 CRC inmates from claiming the good behavior and participation credits of Penal Code section 2931.
I disagree. I share the view of Justice Werdegar, as expressed in her dissenting opinion, that Welfare and Institutions Code section 3201, subdivision (c) specifically incorporates Penal Code section 2931 as it existed in 1980, when subdivision (c) was added to Welfare and Institutions Code section 3201. At that time, the 1982 amendment to Penal Code section 2931 now relied on by the majority did not exist, and therefore is of no effect.
I write separately to point out that even if the majority were correct in concluding that because of the Legislature’s 1982 amendment to Penal Code section 2931, this statute’s good behavior and participation credits are no longer available to CRC inmates, Welfare and Institutions Code section 3201 may nevertheless entitle them to earn essentially identical credits under a related statute, Penal Code section 2933.
Before the Legislature’s amendment in 1980 of Welfare and Institutions Code section 3201, subdivision (c), affording those committed to CRC the same system of credits available to prison inmates, the statutory scheme allowed prisoners, but not felons who, because of drug addiction, were committed to CRC, to receive credit for good behavior and participation *127under Penal Code section 2931. In addition, the potential length of a CRC commitment exceeded the prison sentence for most drug-related offenses (CRC commitments could last up to seven years, with a possible three-year extension). Not surprisingly, many felons eligible for a commitment to CRC and its attendant drug treatment chose instead to go to prison, where they would serve shorter sentences and they could earn good behavior and participation credits, thus reducing their term of confinement. This led to a drastic decline in the number of CRC commitments. (In re Jiminez (1985) 166 Cal.App.3d 686, 692-693 [212 Cal.Rptr. 550]; Cal. Dept, of Corrections Task Force: Study of the Civil Addict Program in Relationship to the Determinate Sentencing Law (1979) pp. 4-6.)
To encourage drug users convicted of felonies to undergo treatment at CRC, the Legislature in 1980 amended Welfare and Institutions Code section 3201 to provide, as relevant here, that the length of a CRC commitment would be “equal to that which [the person committed] would have otherwise spent in state prison had sentence been executed, including application of good behavior and participation credit provisions of Article 2.5 (commencing with Section 2930) of Chapter 7 of Title 1 of Part 3 of the Penal Code” (Pen. Code, § 2931, subd. (c)); in other words, felons committed to CRC can earn the same credits available to prison inmates (People v. Williams (1991) 232 Cal.App.3d 1643, 1646 [284 Cal.Rptr. 241]; In re Jiminez, supra, 166 Cal.App.3d at p. 693; Review of Selected California Legislation (1980) 12 Pacific LJ. 235, 367). This provision remains in effect today.
The Legislature has, however, modified the statutory credit provisions for prison inmates by denying good behavior and participation credits under Penal Code section 2931 to felons who committed their crimes on or after January 1, 1983. (Pen. Code, § 2931, subd. (d).) Generally, those individuals can now earn one of two types of credits set forth in Penal Code section 2933, subdivision (a).1 Thus, prisoners enrolled in a qualified work, training or education program receive one day of credit (often called worktime credits) for each day spent in the program. And prisoners who are willing to participate in a qualified program, but who are not assigned to one, “shall receive no less credit than is provided under [Penal Code] Section 2931” (Pen. Code, § 2933, subd. (a)), meaning that a state prisoner who is willing to participate in a credit-qualifying assignment, but who is not so assigned, *128is entitled to one day of credit for every two days spent in custody, the measure of credits “provided under Penal Code Section 2931.”2
The pertinent question here is this: Under Welfare and Institutions Code section 3201, subdivision (c), can a felon committed to CRC earn either of the two types of credits—worktime credits and “one-for-two credits”— available to prison inmates through Penal Code section 2933? In my view, although CRC inmates do not qualify for worktime credits under the present statutory scheme, they can receive one-for-two credits under Penal Code section 2933.
As I noted at the outset, subdivision (c) of Welfare and Institutions Code section 3201 requires, for purposes of determining credits, that a felon committed to CRC be treated the same as if incarcerated in the state prison. Thus, we must consider the credits available to prisoners. A prisoner willing to participate in a qualifying assignment but not assigned to a program earns one-for-two credits. (Pen. Code, § 2933, subd. (a).) Consequently, to put CRC inmates on the same footing as prison inmates, as called for by subdivision (c) of Welfare and Institutions Code section 3201, CRC inmates are entitled to earn the same one-for-two credits available to prison inmates.
This conclusion effectuates the purpose of Welfare and Institutions Code section 3201, subdivision (c), by encouraging those who are convicted of felonies and are actual or potential drug addicts to accept a CRC commitment. To withhold the one-for-two credits from those committed to CRC would discourage prisoners from accepting CRC commitments and would treat CRC inmates unequally compared to prison inmates.
Moreover, this conclusion avoids rendering portions of Welfare and Institutions Code section 3201, subdivision (c) meaningless. That provision states that the maximum length of confinement must include the “good behavior and participation credit provisions of Article 2.5 (commencing with Section 2930) of Chapter 7 of Title 1 of Part 3 of the Penal Code . . . .” In couching the statutory provision in these words, the Legislature must have intended to provide CRC inmates with some sort of credits. As I discussed earlier, the only potentially applicable types of credits contained in article 2.5 are those in Penal Code sections 2931 and 2933. According to the majority, CRC inmates are not entitled to any credits under section 2931. That leaves us with Penal Code section 2933. If CRC inmates were denied *129the one-for-two credits of Penal Code section 2933, the pertinent language of Welfare and Institutions Code section 3201, subdivision (c), which states that the maximum length of confinement must include the “good behavior and participation credit provisions of Article 2.5 (commencing with Section 2930) of Chapter 7 of Title 1 of Part 3 of the Penal Code” would be reduced to irrelevant surplusage. “ ‘ “If possible, significance should be given to every word, phrase, sentence and part of an act in pursuance of the legislative purpose.” . . . “[A] construction making some words surplusage is to be avoided.” ’ ” (Woosley v. State of California (1992) 3 Cal.4th 758, 775-776 [13 Cal.Rptr.2d 30, 838 P.2d 758], citation omitted.)
For the reasons I have articulated, I would reverse the judgment of the Court of Appeal.
The Legislature has recently provided that inmates convicted of certain serious felonies can earn only a greatly reduced amount of credit (Pen. Code, § 2933.1), and that those who commit other particularly violent crimes are not entitled to any credits (Pen. Code, § 2933.5). Almost all of such felons would be ineligible for commitment to CRC. (See Welf. & Inst. Code, § 3052.) I do not address the question of whether such felons, in the unlikely event of CRC commitment, could earn credits under Penal Code section 2933.
Although these credits are identical to the good behavior and participation credits authorized in Penal Code section 2931, Penal Code section 2933 does not label them, instead referring to them simply as “credits.” For convenience, I refer to them as “one-for-two credits,” because, like the credits awarded under Penal Code section 2931, there is one day of credit for every two days of incarceration.