This article presents results of a study using grounded-theory methodology to explore the meaning of infertility to those persons experiencing it. Thirty-two persons were interviewed, including 15 married couples and two married women whose husbands were either unable or unwilling to participate in the study. Forty-five semistructured interviews were conducted, as each person was interviewed separately and 13 couples were interviewed conjointly. Through the ongoing process of data collection and analysis, a substantive grounded theory was generated, with a core concept being that as persons experience unwanted infertility they take on a central identity of themselves as infertile. The process of taking on and managing this identity is described.