Modern definitions of complete mental health include both positive and negative indicators of psychological functioning. We examined the associations between peer relationships (victimization and receipt of prosocial acts) and multiple indicators of mental health that represent subjective well-being (i.e., life satisfaction, positive and negative affect) and psychopathology (general internalizing symptoms and externalizing problems--aggressive behavior) among 500 high school students in Grades 9 to 11. Peer experiences explained the most variance in positive affect (R[superscript 2] = 18%) and internalizing psychopathology (R[superscript 2] = 19%). Different types of peer experiences drove these effects, with relational victimization particularly salient to internalizing psychopathology and prosocial acts by peers most predictive of positive affect. Moderation analyses indicated that peers' prosocial acts did not serve a protective role in the associations between victimization and mental health. Instead, the presence of overt victimization negated the positive associations between prosocial acts and good mental health (high life satisfaction, low internalizing psychopathology). Understanding these associations illuminates the range of student outcomes possibly impacted by victimization and suggests that both limiting peer victimization and facilitating positive peer experiences may be necessary to facilitate complete mental health among high school students.