Social media engagement is common among adolescents, yet not all adolescents use social media in the same ways or experience the same adjustment correlates. This study examined four social media behaviors (self-disclosure, self-presentation, lurking, and social monitoring) and two time-based measures of social media use (daily number of hours on social media and frequency of social media use) on three developmentally relevant adjustment correlates (internalizing problems, prosocial support, and online peer victimization). Self-report data were collected from 426 middle-school students (54.2% female, 73.6% Caucasian, 11.5% Black, 4.8% Hispanic, 10.1% other ethnicity, mean age = 12.91). The findings showed distinct adjustment patterns among the social media engagement indices, as well as sex and age differences. Neither the number of hours on social media nor social monitoring were associated with any adjustment correlates; however, the frequency of social media use was associated with positive adjustment (less internalizing problems and more prosocial support), primarily for older adolescents. Self-disclosure was positively associated with online peer victimization (girls only) and prosocial support. Self-presentation was associated with higher levels of internalizing problems and online peer victimization, as well as less prosocial support for younger adolescents and boys. Lurking was positively associated with internalizing problems. The findings suggest the need to consider specific types of social media engagement when creating prevention and intervention programs to address adolescent maladjustment.