In the 1970s, the "best interests of the child" doctrine focused custody litigation away from parental competition and toward meeting each child's needs. Yet, artifacts of the parental preference doctrine remain entrenched in custody law and practice. The evolving "best interests" paradigm requires redefining "custody" as development, implementation, and adaptation of individualized plans that provide a structure for complementary parenting. This article explores this paradigm shift while providing an introduction to the realities of child custody proceedings and family law courts. The article also identifies the ways in which mental health professionals can work most effectively with the legal system for the benefit of children of divorce and separation.