This dissertation examined the peer relationships of 56 adolescents with Gender Identity Disorder (M age, 16.94 years; range, 13-20 years), compared to 47 adolescents referred for other clinical concerns (M age, 17.01; range, 13-20 years) and 55 non-referred adolescents (M age, 16.91; range 12-20 years). Adolescents completed self-report questionnaires measuring their gender identity, experiences of peer social support and bullying, and psychosocial adjustment. Consistent with past qualitative research (e.g., Wilson, Griffin & Wren, 2005) and preliminary quantitative evidence (Zucker, Owen, Bradley & Ameeriar, 2002), adolescents with GID reported being bullied significantly more than gender-typical non-referred peers. Compared to all controls, adolescents with GID reported having fewer friends in general, fewer same-sex friends in particular, friendships of shorter duration, and reported experiencing less support from same-sex peers. Group differences in friendship variables for online relationships were not evidenced. Results showed several bullying and friendship variables to be associated with psychosocial difficulties, with gender/sexual bullying and support from same-sex school friends both mediating the relation between gender dysphoria and psychological problems. Findings support the minority stress hypothesis (Meyer, 1995) and contribute to an understanding of the peer relationships of adolescents with GID. Clinical and theoretical implications are discussed.