The current study compared the peer relationships and well-being of 60 sexual-minority (i.e., nonheterosexual) and 65 heterosexual youths between the ages of 15 and 23. Sexual-minority youths had comparable self-esteem, mastery, and perceived stress as did heterosexuals, but greater negative affect. Younger sexual-minority male adolescents had smaller overall peer networks than did young male heterosexuals, whereas older male and female sexual minorities had larger numbers of extremely close friends within their networks than did heterosexuals. Younger sexual-minority adolescents had lost or drifted away from more friends than did heterosexuals. Regardless of age, sexual-minority youths reported disproportionately high worries about losing friends, low feelings of control in their romantic relationships, and fears of never finding the type of romantic relationship they wanted. Sexual-minority youths that were “out” to more heterosexual peers had larger peer networks but more friendship loss and friendship worries. Youths' relationship experiences and concerns mediated sexual identity differences in negative affect.