Female-to-Male transgenders (FTM), or transmen, have become an increasing presence in the gay community, especially in San Francisco. However, there is little data regarding how they transitioned into the gay community and the risks for HIV and STDs that they faced when they completed transition. This dissertation is comprised of four papers that examine that situation. The first paper describes the ways in which three decades of the HIV epidemic have impacted sexual behavior and attitudes within the gay community. That is followed by a review of what is known and unknown about the development of sexual differentiation and gender identity, with a specific focus on a variety of intersex conditions. The final two papers present the results of the study "Sexual Identity, Behavior, and Risk Among Female-to-Male Transgender Persons". This study used Interpretive Phenomenology to describe and understand the experience of 17 transmen who were recruited in the San Francisco area. Two lines of inquiry were identified for the study. The first was to describe and understand the variability in sexual orientation and behavior among transmen before and after transition and the use of testosterone. The four distinct groups of steadfast, shifted, aligned, and fluid are identified and described in the third paper. The final paper examines the second line of inquiry. This was to identify the risk present for transmen who transitioned into the gay community. Risks inherent in being part of the gay community as well as aspects of risk that are specific to transmen are discussed.