Infertility as a life event can be understood from a number of conceptual perspectives: a developmental crisis, a grief reaction, a disruption of marital contracts and roles, a crisis of identity, sexuality, and/or values, or a challenge of decision-making processes. Stress theory and the construct of boundary ambiguity can augment the understanding of the crisis of infertility by providing a different approach and unique perspective. It is the hypothesis of this article that the involuntarily childless couple may experience infertility as a stress of boundary ambiguity, that is, not knowing who is in and who is out of the family system. As infertile couples attempt to make the transition to parenthood they may experience the child they wish to have as a family member who is psychologically present but physically absent.