(concurring in part and dissenting in part, with whom Marshall, C.J., and Ireland, 1, join). An obligation to support a child can be created by express or implied agreement (as the court recognizes because the proposition is indisputable) *535or by conduct showing that the party to be charged has affirmatively committed to the obligation (equally indisputable). Based on the strong findings of the judge in the Probate and Family Court, there is an enforceable obligation to pay support here.
a. I agree that parenthood by contract is not the law in Massachusetts, for the reason, if no other, that parenthood is a status conferred by law and not one that can be conferred by a private agreement to which the child is not (and cannot be) a party. See R.R. v. M.H., 426 Mass. 501, 512 (1998). Both the Legislature and this court have stated many times, and in many contexts, that the Probate and Family Court has full authority to review any agreement within its purview that implicates a child’s best interests. Parenthood by contract could oust, or at least weaken, the established power of the court to protect the child’s best interests. See, e.g., White v. Laingor, 434 Mass. 64, 66 (2001); E.N.O. v. L.M.M., 429 Mass. 824, 831 n.9, cert denied, 528 U.S. 1005 (1999), citing Wilcox v. Trautz, 427 Mass. 326, 334 & n.7 (1998); Adoption of Thomas, 408 Mass. 446, 449-450 (1990).
b. The inquiry, however, does not end here. The judge, who heard testimony from eight witnesses and examined numerous exhibits during three days of trial, made careful findings and concluded that: “The decision to create this child was even more conscious and deliberate than the decision that is made by some couples who are both biological parents and conceive a child by direct sexual intercourse. That was the agreement: to create a child. First the parties explored the ways to accomplish that agreement and then they went forward together to accomplish it.” The defendant cannot be held to be a parent by contract, but her agreement with the plaintiff includes a promise to support the child that she and the plaintiff agreed to create (by way of artificial insemination) and to parent together. That promise to support is well established by the judge’s findings and should not be facilely cast aside as the court does. Because strict adherence to the facts is critical to my analysis, I set forth verbatim, in an Appendix, those findings on which I ground my conclusion that promises were made to parent (that are unenforceable) and to support (that are enforceable). A person *536cannot participate, in the way the defendant did, in bringing a child into the world, and then walk away from a support obligation.
The plaintiff ultimately seeks an order of child support. The Legislature has long recognized the importance of child support for all children. It has expressed, in unmistakable terms, that “dependent children shall be maintained, as completely as possible, from the resources of their parents” and not by the taxpayers, and that support determinations should be made in “the best interests of the child.” G. L. c. 119A, § 1. G. L. c. 209C, § 9 (c). See Department of Revenue v. Mason M., 439 Mass. 665, 669 (2003); L.W.K. v. E.R.C., 432 Mass. 438, 444 & n.17 (2000). With respect to children born out of wedlock, the Legislature has declared that “[c]hildren bom to parents who are not married to each other shall be entitled to the same rights and protections of the law as all other children.” G. L. c. 209C, § 1. See Youmans v. Ramos, 429 Mass. 774, 780 (1999). The Legislature has in many ways “affirmatively supported the assistive reproductive technologies” that enable couples to conceive children in the absence of sexual intercourse. Woodward v. Commissioner of Social Sec., 435 Mass. 536, 546-547 (2002), citing G.L. c. 46, § 4B; G. L. c. 175, § 47H; G. L. c. 176A, § 8K; G. L. c. 176B, § 4J; G. L. c. 176G, § 4. In G. L. c. 46, § 4B, the Legislature made clear that the parentage of children bom as a result of artificial insemination does not depend on biology but may be determined on the basis of consent. See R.R. v. M.H., supra at 510 (§ 4B “concem[s] the status of a child bom to a fertile mother whose husband, presumably infertile, consented to her artificial insemination with the sperm of another man so that the couple could have a child biologically related to the mother”). We have stated that “[r]epeatedly, forcefully, and unequivocally, the Legislature has expressed its will that all children be ‘entitled to the same rights and protections of the law’ regardless of the accidents of their birth.” Woodward v. Commissioner of Social Sec., supra at 546. The Legislature has yet to contemplate the situation here.
The plaintiffs resort to the equity jurisdiction of the Probate and Family Court is entirely appropriate. That our statutes offer the plaintiff no remedy, because the defendant is not a legal par-
*537ent, does not preclude an order of child support. Cf. E.N.O. v. L.M.M., supra at 828 & n.4 (visitation). The Legislature has declared that the Probate and Family Court “shall have original and concurrent jurisdiction with the supreme judicial court and the superior court department of all cases and matters of equity cognizable under the general principles of equity jurisprudence and, with reference thereto, shall be courts of general equity jurisdiction.” G. L. c. 215, § 6. This grant of equitable power is plenary and “extends to actions necessary to afford any relief in the best interests of a person under [the court’s] jurisdiction.” Matter of Moe, 385 Mass. 555, 561 (1982). See Eccleston v. Bankosky, 438 Mass. 428, 437 (2003). See also Police Comm’r of Boston v. Municipal Court of the Dorcester Dist., 374 Mass. 640, 660-665 (1978). This authority extends as well to the specific enforcement of agreements, including, as here, one to support a child. See Ross v. Ross, 371 Mass. 439, 439-440 (1976) (separation agreement); Suga v. Maum, 29 Mass. App. Ct. 733, 736 (1991) (agreement to convey land); Ross v. Friedman, 22 Mass. App. Ct. 513, 515-516 (1986) (agreement to sell shares of stock).1 It is also significant that, in 1986, the Legislature built on the Probate and Family Court’s general equity jurisdiction by authorizing it to hear complaints to establish paternity or to order child support for children bom out of wedlock and vesting it with sole jurisdiction to decide requests for custody and visitation of such children. G. L. *538c. 209C, § 3, inserted by St. 1986, c. 310, § 16.2 The Legislature, thus, has conferred on the Probate and Family Court broad equitable authority (including the power to compel specific performance) that, although not unbounded, extends to deciding many specific and complex child-related issues that have not been foreseen by statute. See E.N.O. v. L.M.M., supra at 827-828; Superintendent of Belchertown State Sch. v. Saikewicz, 373 Mass. 728, 755-756 (1977). See also, e.g., Eccleston v. Bankosky, supra at 437; Culliton v. Beth Israel Deaconess Med. Ctr., 435 Mass. 285, 291-292 (2001); E.N.O. v. L.M.M., supra at 833-834; Youmans v. Ramos, supra at 779-780; Gardner v. Rothman, 370 Mass. 79, 80 (1976).
The existence of an agreement to support on the part of the defendant, buttressed by society’s interests (as expressed through our statutes and our case law) and the best interests of the child standard, requires relief here.3 See A.R. v. C.R., 411 Mass. 570, 575-576 (1992). This conclusion finds support in decisions of courts in other jurisdictions involving facts of a similar nature. See Chambers vs. Chambers, No. CN 00-09493 (Del. Fam. Ct. Feb. 5, 2002); L.S.K. v. H.A.N., 813 A.2d 872, 878-879 (Pa. Super. Ct. 2002). See also In re Marriage of Buzzanca, 61 Cal. App. 4th 1410, 1412 (1998). But see State ex rel. D.R.M. v. Wood, 109 Wash. App. 182, 189, 195 (2001) (conclud*539ing that mother’s former same-sex partner not obligated to pay child support because not parent under Uniform Parentage Act).
The conclusion is also in accord with those principles of the American Law Institute’s (ALI) Principles of the Law of Family Dissolution, which, insofar as this case is concerned, recommend imposing a parental support obligation on a “person who may be not the child’s parent under [SJtate law, but whose prior course of affirmative conduct equitably estops that person from denying a parental support obligation to the child.” ALI Principles of the Law of Family Dissolution: Analysis and Recommendations § 3.03 & comment c (2002).4 Section 3.03(l)(c) allows imposition of an order of support when a child is conceived “pursuant to an agreement between the person [to be charged] and the child’s parent that they would share responsibility for raising the child and each would be a parent to the child.” Where the conception of a child is achieved *540through artificial insemination, comment c Suggests that, in the case of married or unmarried couples that execute a procreation agreement, the man “is to be treated as the father for purposes of child support.” Id. at 417. In the case of same-sex couples that “wish to have children together [by way of] a sperm donation or a surrogate mother,” a support obligation may be imposed on a party “who is not a parent but who has made a [§ 3.03(l)(c)] agreement with the child’s parent.”5 Id.
In summary: even though we do not recognize parenthood by contract, an agreement between the parties has been proved, which includes a promise of support, and the Probate and Family Court, acting under G. L. c. 215, § 6, has jurisdiction to hear the case and specifically to enforce that promise.6 That the defendant may regret her words and conduct, and view the remedy as harsh, is of no consequence. Equity does not relieve from difficult agreements simply because they are regretted. The child may have been abandoned by the defendant, but he should not be abandoned by the court.
*541Appendix.
“33. In June of July, 1999, [the defendant] called [the plaintiff] at work and told her that she had changed her mind and that she wanted to have a child. [The plaintiff], surprised and interrupted in the middle of a busy work day, suggested that they talk more about it that evening.
“34. In the evening, the discussion continued. According to [the plaintiff], it was a long and detailed discussion lasting though dinner and far into the night. She recalled Tots of excitement and fear’ on the part of each of the parties. The discussion included (a) [the defendant’s] statement that she had always wanted a boy, felt more comfortable with a boy; (b) [the plaintiff’s] repeatedly asking, ‘are you sure?’ and ‘What made you change your mind?’; (c) the possibility of using [the defendant’s] brother’s sperm; (d) the ethics of sperm donation; (e) [the defendant’s] dream of driving with a little son with sun glasses on; (f) the division of labor between them for household chores; (g) the need for bigger housing; (h) a school district for the child; (i) Baptism and the selection of Godparents; (j) [the plaintiff’s] own physical problems and the risk of pregnancy, and their agreement that there would be no pregnancy if the medical risks were too great to [the plaintiff] because [the defendant] did not want to risk losing [the plaintiff].
“45. According to [the plaintiff], the parties discussed whether or not to continue with the insemination. They discussed the alternatives of adoption and a foster child. They discussed the idea of [the defendant’s] being the birth mother. Because [the defendant] has a degenerative disk in her back and would have had an even more difficult pregnancy than [the plaintiff], the parties decided to continue with the process of [the plaintiff’s] insemination.
“47. [The defendant] determined that it would, in [the plaintiff’s] words, ‘be too weird’ to raise her brother’s child as her own, and the parties determined to go forward with insemination by an anonymous sperm donor.
“48. At the next appointment, on August 6, 1999, the parties both signed the Consent Form, Donor Insemination. The document was signed in front of an employee of [the physician] after approximately [forty-five] minutes of discussion with a nurse.
“53. The same issues which had informed their earlier discussions continued to be discussed between the parties: the expenses involved in raising a child, their excitement, their fears, jokes about what they would do if the child were a girl. They brainstormed solutions to their fears and poked fun at each other.
“55. The first insemination occurred in October, 1999, in [the physician’s] office. Both parties were present. It was not a successful insemination. The parties felt upset. [The plaintiff] reported that [the defendant] put her head down and shook it at news of the failure.
“56. Each insemination cost $250.00. The parties discussed how many they could afford and agreed to purchase two. They deferred any discussion of what to do if the second one failed.
“57. The second insemination, which took place in December, 1999, was successful.
“62. In February and early March, 2000, the parties’ relationship deteriorated. Though they lived together, [the defendant] began to go out more frequently with [a friend].
*542“63. The parties’ discussions about the pregnancy continued throughout February and March.
“64. In April, 2000 [the defendant] broke up with [the plaintiff]. In sometimes intense conversations, [the defendant] would express tearfully her concern that she would be the ‘separated- parent’ and not see the child as much, that she wanted to adopt the child, promised financial support and promised to talk later about the details since she wanted just to focus on the break-up of the relationship at that time. [The defendant] said she never wanted to do what her own father did in abandoning the child and refusing to pay child support.
“65. In May, 2000 [the defendant] moved out of the apartment, and the parties divided their joint money. By that time they were no longer speaking to each other.
“66. The parties paid for all expenses of insemination and pre-natal care from their joint funds.
“67. On July 1, 2000, [the plaintiff] went into premature labor [and] gave birth to [the child] 9 weeks early.
“68. [The plaintiff] was in shock and disbelief, but she was physically in good condition. The baby did not need to be delivered by Caesarian section. He was, however, in such serious condition that he was rushed away from her at birth, and she was not even able to see his face.
“69. [The defendant], in response to a telephone call from [the plaintiffs] sister, arrived at the hospital approximately an hour after the birth.
“70. The parties saw the child together for the first time. [The defendant] gave [the child] his first bottle. The hospital issued each party an identification bracelet indicative of parenthood.
“71. [The defendant] remained overnight at a hotel near the hospital and asked [the plaintiff] to speak with her regarding any medical decisions necessary for the child.
“72. [The defendant] told [the plaintiff’s sister] that she would support the child and would change her work hours to help raise the child.
“75. [The defendant] visited the baby two more times at the [hospital]. There were discussions between the parties about finances ([the defendant] gave [the plaintiff] $800) and about [the plaintiff’s] discomfort with [the defendant’s] having introduced [her friend] into the visits. [The friend], formerly a good friend of [the plaintiff], had become [the defendant’s] new partner.
“76. [The defendant] sent pictures of herself and the child out on the Internet on July 26, 2000 to friends accompanied by the message: T hope you all enjoy the pics of my wonderful, beautiful boy. . . .’
“78. While the child was in the hospital, the parties had a number of discussions about their plans for parenting the child. They discussed the possibility of [the defendant] watching the child half-days or obtaining a new job that would allow her to spend more time with the child.
“79. [The defendant] continued until as late as August, 2000 to reiterate her wish to support the child.
“80. On October 27, 2000, the parties met outside [the plaintiff’s] office and argued for approximately [one and one-half] hours about child support. [The plaintiff] at the time was working full time and parenting the child who, *543as a result of his premature birth and the resulting medical problems, was treating with three different specialists.
“81. In the argument, [the defendant] offered to take the child if he were such a burden to [the plaintiff], [The plaintiff] responded that she was not asking to be relieved of the child but only wanted financial assistance.
“82. [The defendant] acknowledged that she was not paying child support because she was angry at [the plaintiff] about the arguments they were having.
“83. [The plaintiff] testified that she received a letter (the original of which has been lost). The copy of the letter (offered over objection and taken de bene) is undated and unsigned, and, although it bears a postmark which indicates that it was mailed on October 31, it shows no legible year. The letter is addressed to [the plaintiff’s first name] and it refers to [the child’s first name]. It relates the reasoning of the writer who has decided not to have any further relationship with [the child] ‘for the well-being of my son.’
“84. The Court finds that the letter was written by [the defendant] in late October, 2000. In the letter, [the defendant] expresses her intention to have no further interaction with the child. It asserts that [the defendant’s] motivation is to protect [the child] by her withdrawal from his life. She asserts her love for the boy. She ends by requesting that [the plaintiff] stop contacting her at all.”
The court’s power to compel compliance with an agreement is not limited to circumstances where performance is promised in return for traditional consideration but includes those where the party held liable is bound by another’s reasonable reliance on the promise. We do not use the term “promissory estoppel,” but have treated the principles of estoppel as sufficient to create a contract. See Cataldo Ambulance Serv., Inc. v. Chelsea, 426 Mass. 383, 386 & n.6 (1998); Loranger Constr. Corp. v. E.F. Hauserman Co., 376 Mass. 757, 760 (1978). The prerequisites for a successful claim based on a theory of promissory estoppel are met in this case: (1) promises to parent and support a child that (2) the defendant should reasonably have known would cause the plaintiff to proceed with their joint plan for her to become pregnant by means of artificial insemination (3) which the plaintiff did (4) justifiably relying on the defendant’s affirmative conduct and promises, leaving the plaintiff in circumstances such that (5) injustice (to the plaintiff and to the child) can be avoided only by enforcement of the promise to support.
Long before the enactment of G. L. c. 209C, however, the law imposed a duty on parents “to support, provide for and protect the children they bring forth” (at least those children brought forth in a traditional family context). Commonwealth v. Brasher, 359 Mass. 550, 556 (1971), citing 1 Blackstone, Commentaries 446-454 (9th ed.).
My analysis would be no different were the defendant an unmarried male partner who purposefully put himself in the position of a parent, by taking affirmative steps that resulted in the birth of a child whom he considered, for a time, to be his son, but subsequently attempted to disavow all of his parental responsibilities when his relationship with the child’s mother deteriorated. This case is not about establishing parental rights of same-sex couples. It is about the defendant’s taking financial responsibility for a child whom she had promised, by words and deeds, to support. When two adults decide together to create a child by way of artificial insemination, and agree together to assume financial responsibility for that child, and their decision and subsequent conduct leads to the birth of a child, that child is no less entitled to the financial support of both adults than had the adults been married, or had the child been conceived through sexual intercourse and thus was biologically linked to both adults.
Section 3.03 (1) of the American Law Institute’s (ALI) Principles of the Law of Family Dissolution: Analysis and Recommendations (2002) provides that a support obligation may arise when:
“(a) there was an explicit or implicit agreement or undertaking by the person to assume a parental support obligation to the child;
“(b) the child was bom during the marriage or cohabitation of the person and the child’s parent; or
“(c) the child was conceived pursuant to an agreement between the person and the child’s parent that they would share responsibility for raising the child and each would be a parent to the child.”
In determining whether a support obligation is justified, § 3.03(2) of the ALI Principles directs that a judge should consider:
“(a) whether the person and the child act toward each other as parent and child and, if so, the duration and strength of that behavior;
“(b) whether the parental undertaking of the person supplanted the child’s opportunity to develop a relationship with an absent parent and to look to that parent for support;
“(c) whether the child otherwise has two parents who owe the child a duty of support and are able and available to provide support; and
“(d) any other facts that may relate to the equity of imposing a parental support duty on the person.”
Nowhere in the ALI Principles does it state the requirement that this agreement need be in writing. Moreover, comment b of § 2.03, setting forth definitions for purposes of determining custodial responsibilities for children, makes clear that “[a] formal, written agreement is not required to create a parent-byestoppel status.” Principles of the Law of Family Dissolution: Analysis and Recommendations, supra at § 2.03 comment b, at 114 (allowing, however, that “the absence of formalities may also affect the factfinder’s determination of whether an agreement was made”). The proviso in § 7.04(1), cited by the defendant, that “[a]n agreement is not enforceable if it is not set forth in a writing signed by both parties,” is not determinative in this case. Id. at 960. The entire text of chapter 7, as well as its accompanying comments and illustrations, demonstrates that § 7.04 contemplates premarital, marital, and separation agreements, and not agreements purporting to assume responsibility for parenting a child.
The court’s concerns over what rights, if any, the defendant, if ordered to pay child support, might seek in the future with respect to the child address issues that are beyond the scope of this opinion. Ante at 531 n.10. A relationship of financial support between the defendant and the child arguably could entitle the defendant to concomitant rights and responsibilities which, if asserted, would be considered by a judge in the Probate and Family Court under general principles of family law and the best interests of the. child. Speculation as to such matters, however, is not a proper basis on which to deny the relief sought here. The same types of concerns have been raised, and dealt with, in other cases presenting novel or difficult family law issues. See, e.g., Blixt v. Blixt, 437 Mass. 649, 664-665 (2002), cert. denied, 537 U.S. 1189 (2003); E.N.O. v. L.M.M., 429 Mass. 824, 832-833, cert. denied, 528 U.S. 1005 (1999); Adoption of Tammy, 416 Mass. 205, 214-215 (1993).