In the current work, the reliability and validity of a measure of sexual minority identity formation (the Same-Sex Orientation Identity Questionnaire; SSOIQ) was assessed with a racially/ethnically diverse sample. The SSOIQ was developed to measure one's location in a sexual minority identity formation process. The measure was derived from the Fassinger and colleagues (McCarn & Fassinger, 1996)) dual-trajectory model that hypothesizes two separate but reciprocal processes of individual sexual identity development and group membership identity development. Estimates of internal consistency reliability were assessed through Cronbach's alpha. A preliminary evaluation of the theoretical model underlying the measure was conducted by examining the interrelationships of the conceptually distinct phases of the model. Convergent validity was partially established through relationships of the measure to measures of identity confusion, internalized homonegativity, same group orientation, and outness. Discriminant validity was partially established using a measure of dogmatism.