We examined the mediating role of students' interpersonal and academically related social goals in linking students' perceptions of teacher and peer personal and academic emotional supports to their classroom behavior (prosocial, social responsibility) in a sample of young adolescents (n = 3,092) from 7 schools from the mid-Atlantic, Midwest, and Southwest regions of the United States. We tested models at the student level (Level 1) and the classroom level (Level 2), while controlling for incidental school-level effects (Level 3); we utilized new analytic strategies for dealing with small sample incidental clustering (using fixed effect/random effect hybrid models) and convergence issues concomitant with missing data and complex models by coupling Bayesian imputation with frequentist estimation. Our results indicate that relations between student's perceptions of teacher and peer emotional supports for academic and personal well-being and classroom behavior are mediated, in part, by social goal pursuit at Level 1 but not Level 2; relations between social goals and classroom behavior were moderated by Level 2 emotional supports for academics from teachers and peers such that consensus concerning levels of academic support strengthened relations between social goals and behavior. Results differed as a function of the source of information concerning student behavior (peer nominations, teacher ratings) and type of behavior. Educational Impact and Implications Statement: This study suggests that students who believe their classroom teachers and peers are emotionally supportive tend to pursue goals to behave in prosocial (helping, sharing) and socially responsible (following rules) ways. In turn, pursuing these goals predicts students' displays of prosocial and socially responsible classroom behavior. A classroom climate characterized by a teacher's and classmates' strong academic support appears to strengthen these socially relevant outcomes.