OPINION
Before MATTHEWS, C.J., and RABINO WITZ, BURKE, COMPTON and MOORE, JJ. COMPTON, Justice.This appeal arises from an adoption proceeding. The trial court found that the natural mother had for three years failed significantly without justifiable cause to communicate meaningfully with the child. Accordingly the court concluded that the mother’s consent to adoption was not required. See 25.23.050(a).1 The court entered the decree of adoption, terminating the mother’s parental rights. We affirm.
I. FACTS AND PROCEEDINGS.
In January 1979 Irma Addison, then 16 years old, ran away from her home in California and went to Colorado Springs. There she met Rick Danielson and began an intimate relationship with him. In December 1979 she and Rick moved to California. It was there that their child, Becky Sue, was bom in November 1980.
In January 1982 Rick left California and moved to Alaska in hopes of finding employment. He intended to send for Irma and Becky Sue once he found work. Soon after Rick left for Alaska, Irma returned to Colorado Springs. She lived there first with Rick’s mother, Rebecca Danielson, and later with Betty and Jim McDowell as their live-in babysitter. On April 2, 1982, Irma received news that her father was terminally ill. She left Becky Sue in the care of Rebecca Danielson and traveled to California to be with her father.
Several days after Irma’s departure, Mrs. Danielson and Mrs. McDowell reported to the county department of social services that Irma had neglected and abused Becky Sue. The department obtained legal custody of Becky Sue; Mrs. Danielson was granted physical custody of the child. A few days later, Rick flew to Colorado Springs, picked up Becky Sue, and one hour later returned to Anchorage.
Irma remained in California for two weeks. She returned to Colorado Springs to discover that Rick had taken Becky Sue to Alaska. Soon after Irma’s return, Mrs. Danielson told the department of social services that the allegations of abuse and neglect had been false. She also admitted that the false report had been prompted by her fear that she would lose contact with the child.
Several days after Irma’s return, she received a telephone call from Rick. He asked her to visit him in Alaska, but told her that he would not allow her to see Becky Sue. Though Mrs. Danielson offered to pay Irma’s round-trip air fare, Irma did not travel to Alaska.
Irma remained in Colorado Springs, residing first with Mrs. Danielson and again briefly with the McDowells as a babysitter. During this period, Irma spoke to a legal aid attorney about obtaining custody of Becky Sue; he told her that he could not help her.
In July 1982 Irma married Roger Addison and moved with him to Ohio. In March *12241983 a daughter, Jennifer, was born to the couple.
In the years that followed her marriage to Roger, Irma made few attempts to locate or communicate with Becky Sue. At various times she spoke with social workers and attorneys about obtaining custody of Becky Sue, but nothing ever came of the meetings. Irma remained in contact with Rick’s grandmother, whom she knew as “Gram.” The two spoke about Becky Sue, and Irma expressed a desire to raise Becky Sue and Jennifer as sisters. Irma asked for and received photographs of Becky Sue. Irma did not ask where Becky Sue was living, nor did she send any cards or presents to Becky Sue. Irma apparently believed that any attempt by her to communicate with or locate Becky Sue would be futile.
From 1982 to 1985, Becky Sue resided in Alaska. At various times she lived with Rick, Mrs. Danielson, Rick’s sister, Pamela, and her husband, Charles Lord.
In December 1985 Pamela and Charles Lord filed a petition for adoption of Becky Sue. Rick consented to the adoption. Pamela and Charles asserted that because Irma had failed to communicate with Becky Sue for three years, her consent was not required. Irma was notified of the petition, and, after appointment of counsel, she filed an objection.
The case was tried before Judge Thomas E. Jahnke. Judge Jahnke concluded that Irma’s consent was not required and that the adoption was in the best interests of Becky Sue. Accordingly he entered a decree of adoption, terminating Irma’s parental rights. Irma appeals.
II. THE TRIAL COURT DID NOT ERR IN FINDING THAT IRMA’S FAILURE TO COMMUNICATE WITH BECKY SUE WAS WITHOUT JUSTIFIABLE CAUSE.
Consent to an adoption is not required “if the parent for a period of at least one year has failed significantly without justifiable cause, including but not limited to indigen-cy, ... to communicate meaningfully with the child.” AS 25.23.050(a).
Irma concedes that for nearly three years she did not communicate with Becky Sue. She contends, however, that the trial court erred in finding that her failure to communicate was without justifiable cause.
In concluding that Irma’s failure to communicate was without justifiable cause, the trial court made a finding of fact. We will disturb a trial court’s findings of fact only when we are convinced that they are clearly erroneous, that is, when we are left with a definite and firm conviction on the entire record that a mistake has been made. Martens v. Metzgar, 591 P.2d 541, 544 (Alaska 1979).
A parent has the duty to make reasonable efforts to locate and communicate with his or her child. E.J.S. v. State, Dep’t of Health & Social Serv., 754 P.2d 749, 751 (Alaska 1988). Irma’s failure to communicate with Becky Sue was justified only if her efforts to communicate were objectively reasonable in light of the existing circumstances. See D.L.J. v. W.D.R., 635 P.2d 834, 839 (Alaska 1981) (“whether the cause was justifiable must turn on the court’s determination of what grounds are objectively acceptable”).
The prospective adoptive parents have the burden of proving by clear and convincing evidence that the natural parent’s failure to communicate was without justifiable cause. Id. at 838. Further, AS 25.23.050(a) should be strictly construed in favor of the natural parent and against a finding that the failure to communicate was without justifiable cause. Matter of Adoption of K.M.M., 611 P.2d 84, 88 (Alaska 1980).
As Irma points out, significant obstacles made communication with Becky Sue difficult. Irma and Roger were indigent throughout the three-year period; they were a great distance from Alaska; they appear to have lacked legal sophistication. More importantly, the Danielson family engaged in a course of conduct intended to deny Irma access to the child. Rick apparently hoped that by denying Irma access to the child he could force her to reconcile *1225with him. Rick’s mother, fearful that she would lose contact with Becky Sue, filed a false report of child abuse to prevent Irma from obtaining custody of the child. Rick’s grandmother, though she maintained contact with Irma, never offered to give Irma Becky Sue’s address or encouraged Irma to communicate with Becky Sue. Irma’s suspicion that efforts to communicate with Becky Sue would be met with hostility was not wholly without foundation.
Irma points out that she made several attempts to obtain custody of Becky Sue. After returning to Colorado Springs in 1982, Irma spoke with a legal aid attorney and with a district attorney. Apparently the attorneys told her that she would have to have physical custody of Becky Sue before initiating proceedings and that Rick’s actions were not illegal. Irma also may have spoken to two Colorado Springs attorneys in private practice and received similar responses. In 1983, Irma and Roger filed for bankruptcy; Irma asked the bankruptcy attorney if he could help her to obtain custody of Becky Sue, but he did not take the case. Irma also spoke to an Ohio welfare worker, but was again advised that she should obtain physical custody before initiating proceedings. Later, in California, Irma spoke to child protective services. Again her efforts ended when she was told that she would have to obtain physical custody of Becky Sue.
Irma also contends that Becky Sue’s age — she was 16 months old when Rick took her to Alaska — would have made meaningful communication over the phone or by letter unlikely.
Irma’s arguments have some force. Irma apparently believed that any attempt to communicate, short of obtaining physical custody of Becky Sue, would be blocked by the Danielson family. Accordingly her efforts were limited to occasional attempts to obtain custody. Her indigency and her lack of legal sophistication may have contributed to the appearance of half-heartedness that characterized these attempts.
Nonetheless, we conclude that the trial court did not clearly err in finding that Irma’s failure to communicate was without justifiable cause. As the trial court remarked, Irma never tested her assumption that an attempt to communicate with Becky Sue would be blocked. Though she communicated regularly with Rick’s grandmother, she never requested Becky Sue’s address. Further, as the trial court noted, after the adoption proceedings were initiated, and after Irma was provided with Becky Sue’s phone number, “she made only a few attempts to contact Becky Sue by telephone (all or most in a single week) and sent nothing through the mail.”2 Finally, Irma’s sporadic and unsustained efforts to obtain custody of Becky Sue do not rise to the level of “reasonable efforts.” See E.J.S., 754 P.2d at 751.
As Irma points out, the conduct of Rick and Mrs. Danielson may have been intended to deny Irma access to Becky Sue. However, the issue in this case is not the conduct of Rick and his mother, but the conduct of Irma. Rick and Mrs. Daniel-son’s conduct, however reprehensible, did not relieve Irma of her duty to make reasonable efforts to communicate with Becky Sue.3 The trial court found that Irma had *1226failed to make reasonable efforts. This finding is not clearly erroneous.4
III. THE PROVISIONS FOR TERMINATION OF PARENTAL RIGHTS PURSUANT TO AN ADOPTION PROCEEDING ARE NOT UNCONSTITUTIONAL.
Two statutory mechanisms provide for the involuntary termination of parental rights, adoption proceedings and child-in-need-of-aid proceedings. S.J. v. L.T., 727 P.2d 789, 795 (Alaska 1986). In an adoption proceeding, the court may terminate the parental rights of a natural parent if it determines:
(1) parental consent to adoption is not required; and
(2) adoption is in the best interests of the child.
AS 25.23.050; AS 25.23.120(c); AS 25.23.-130(a). In a child-in-need-of-aid proceeding, the court may terminate the parental rights of a natural parent if it determines:
(1) there is a child in need of aid under 47.10.010(a)(2) as a result of parental conduct; and
(2) the parental conduct is likely to continue.
AS 47.10.080(c)(3).
Irma contends that this statutory scheme distinguishes without rational basis two groups of parents:
(1) parents whose children are the subjects of adoption proceedings; and
(2) parents whose children are not the subjects of adoption proceedings.
Irma contends that the statutory scheme therefore violates on its face both equal protection and substantive due process of law.
Irma asserts that the shared purpose of the two statutory termination mechanisms is to terminate the rights of unfit parents. That a child is the subject of an adoption proceeding says nothing about the fitness of the child’s parent. Therefore, Irma contends, by applying in adoption proceedings a more stringent standard of parental conduct,5 the legislature has classified parents on the basis of a factor without rational relation to the purpose of the adoption statute.
Viewed broadly, termination of parental rights incident to adoption proceedings and termination incident to child-in-need-of-aid proceedings serve the same compelling purpose: advancing the best interests of children. Viewed more closely, the two mechanisms serve quite different purposes. Matter of Adoption of R.H.A., 702 P.2d 1259, 1265 (Wyo.1985). An adoption proceeding operates to replace a parent, while a child-in-need-of-aid proceeding operates to emancipate a child from an offending parent’s legal bonds. Davis v. Davis, 708 P.2d 1102, 1112 (Okla.1985). Through an adoption proceeding a child may be placed in a stable, permanent home; through a child-in-need-of-aid proceeding a child may be placed in an environment which, though *1227uncertain, is preferable to the dangerous environment he or she occupies. See Watkins v. Dudgeon, 270 Ark. 516, 606 S.W.2d 78, 81 (1980).6
The different purposes of the two statutory mechanisms justify the use of different standards.7 A parent’s conduct, though not so dangerous as to warrant placement of the child with the state, may nonetheless justify disregarding the parents’ refusal to consent to adoption. Cf. Matter of Adoption of R.H.A., 702 P.2d at 1265 (rejected similar constitutional challenge on ground that “[t]he two statutes in question do not serve identical purposes, and appellant has not cited authority or suggested any logical reason why the two statutes should have identical standards”). Irma’s constitutional argument is therefore without merit.8
The judgment of the superior court is AFFIRMED.
RABINOWITZ, J., with whom MATTHEWS, C.J., joins, dissenting.
. AS 25.23.050(a) provides in part:
Consent to adoption is not required of
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(2) a parent of a child in the custody of another, if the parent for a period of at least one year has failed significantly without justifiable cause, including but not limited to indi-gency,
(A) to communicate meaningfully with the child....
. Irma contends that this statement by the trial court is not supported by thé record and that Irma’s conduct during 1986 is not relevant to the question before the trial court. The trial court’s statement is supported by the record. Irma’s conduct after notification of the adoption proceeding is relevant to the question whether her earlier failure to communicate was without justifiable cause: her conduct in the absence of obstacles to communication might help the court to determine whether her earlier failure was in fact the result of obstacles to communication or merely the result of a lack of will.
. The dissent’s reliance on S.M.K. v. R.G.G., 702 P.2d 620 (Alaska 1985), is misplaced. In S.M.K., as in this case, the father and his family engaged in conduct intended to deny the mother access to the child. Id. at 621. There the resemblance ends.
The mere fact that a parent is at some point wrongfully denied access to the child is not dispositive of the issue of justification. The court must consider as well the efforts of the parent to overcome the denial. Though the mother in S.M.K. was denied access to her child, she attempted with diligence to obtain her child’s return. Id. In contrast Irma appeared to be resigned to the loss of Becky Sue. Her efforts to obtain Becky Sue’s return were sporadic and unsustained.
*1226It should also be observed that in S.M.K., this court merely affirmed a trial court’s finding that the failure to communicate was justified. Thus, even if the facts in the two cases were identical it would not follow that the trial court’s finding in this case should be set aside as clearly erroneous. The trial court heard lengthy, in-court testimony from Irma, Rebecca Danielson and others. To all appearances, it rendered a careful and thoughtful decision. The clearly erroneous standard demands that we defer to the trial court in this matter.
. Irma asserts that, because she filed a complaint for custody of Becky Sue during the pendency of the adoption proceedings, the court should have applied AS 25.20.060(a), which requires the court to award custody on the basis of the best interests of the child. This, she asserts, the court did not do.
AS 25.23.120(c) requires the trial court in an adoption proceeding to determine whether the adoption is in the best interests of the person to be adopted. Where a complaint has been filed as well under AS 25.20.060, and the court determines that adoption is in the child's best interests, this determination effectively serves as a determination that custody in the complaining parent is not in the child’s best interest.
The trial court in this case found that adoption by the Lords was in Becky Sue's best interests. Thus, the court properly denied Irma’s complaint for custody.
. Curiously, in her opening brief Irma asserts that the criteria for termination of parental rights under AS 47.10.080 "are much more lax” than those under AS 25.23.050.
. The drafters of the Uniform Adoption Act, upon which AS 25.23.050 is based, remark in a prefatory note,
While many juvenile court acts contain provisions for terminating parental rights, many of these acts by concentrating on the fault of a particular type of parent are inadequate where the objective is termination of the parental right to control adoption.
Unif. Adoption Act 9 U.L.A. 11 (1971).
. In Matter of Adoption of K.S., 543 P.2d 1191 (Alaska 1975), this court discussed the two mechanisms:
There appears to be no rational basis for the application of a lesser standard of proof in adoption cases since a finding of unfitness would incur the same result: a termination of parental rights.
Id. at 1195. Irma relies on this remark in arguing that no basis exists for the use of different standards in each of the mechanisms.
Irma’s reliance is misplaced. The purport of the remark is not that no basis exists for applying different standards of parental conduct; rather that no basis exists for applying different standards of proof. The court merely held that the "clear and convincing evidence” standard of proof should be applied in both proceedings. Id. Thus, Matter of K.S. is inapposite.
.Irma's argument is merely that the statutory classification is without rational basis, and that the classification therefore violates state and federal equal protection and state and federal substantive due process. Federal equal protection and state and federal substantive due process appear to require only a rational basis. See Concerned Citizens of South Kenai Peninsula v. Kenai Peninsula Borough, 527 P.2d 447, 452 (Alaska 1974); Lehr v. Robertson, 463 U.S. 248, 268 n. 27, 103 S.Ct. 2985, 2997 n. 21, 77 L.Ed.2d 614, 631 n. 27 (1983). Because Irma has not raised the question, we do not consider the question whether a more stringent analysis of the means adopted by the legislature may be appropriate under state equal protection law. See Alaska Pacific Assurance Co. v. Brown, 687 P.2d 264, 269 (Alaska 1984).