Despite having recognized the constitutional rights of parents almost a hundred years ago, the Supreme Court has not weighed in on the subject of who qualifies as a “parent” under the Fourteenth Amendment in thirty years. In light of the Court’s silence, the states have been forced to individually grapple with the issue of constitutional parenthood—a task made exponentially more difficult by the fact that the last thirty years have ushered in an avalanche of change when it comes to the American family. With such societal changes as advances in assisted reproduction, the legalization of same-sex marriage, and the increased frequency of divorce, remarriage and cohabitation, states now regularly encounter claims of parental identity that thirty years ago would have been unimaginable. Nonetheless, the states have persevered, adopting a number of approaches to deal with these increasingly thorny issues. The problem, however, is that the constitutional protections that are afforded parents now vary by state. Even more troubling is the fact that some states have defined “parent” in such a way as to discriminate against those families that do not comport with those states’ conception of the “ideal” family. To solve this problem, this Article makes two proposals. First, the Supreme Court must offer more guidance on how states may define constitutional parenthood. Although a definitive definition of the term is both impractical and unrealistic, the Court can and should delineate the outer boundaries of that constitutional standard. Second, taking a cue from some of the tests developed by the states, this Article proposes what exactly those boundaries should be so as to help craft a definition of constitutional parenthood that is more responsive to and protective of the twenty-first century family.