The purpose of this grounded theory study was to explore the process of college men's gender identity development. Conducted from a social constructivist epistemological paradigm, through a social justice theoretical lens, and using a constructivist grounded theory methodology, the following research questions guided this study: (a) how do college men come to understand themselves as men; (b) how does this understanding of what it means to be a man change over time, if at all; and (c) what are the critical influences on this process? Three interviews with 10 college men from a large East Coast university were conducted.The theory that emerged from this study is grounded in the participants' experiences and depicts gender identity as developed through constant interaction with society's expectations of them as men. In order to try to meet these expectations and be seen as men, participants described putting on a performance that was like wearing a mask or "putting my man face on." This process included learning societal expectations of them as men, as well as specific cultural group expectations. The men in this study were all aware that they did not neatly fit behind the mask, either as a result of personal characteristics or social identities. Their resulting insecurities led them to wearing the mask both consciously and unconsciously so that they would be seen as men by society.Wearing the mask had consequences for the women in their lives, their relationships with other men, and themselves as they were also denying or masking their true selves.Although none of the men in this study had been able to completely take off the mask, they were able to identify critical influences in their lives that had helped each of them begin to remove the mask in certain circumstances and begin moving towards being their own man. This theory of college men's gender identity development has implications relevant to theory development, research, student affairs practice, and social justice.