The purpose of this study was to examine whether seventh-grade positive peer affiliation and conduct problems mediated the relationship between sixth-grade parental monitoring of behavior and eighth-grade school participation and grades among students with elevated behavior ratings (EBR; n = 821) and students with unelevated behavior ratings (UBR; n = 3,779). Conduct problems and peer affiliation mediated the relationship between parental monitoring and school participation as well as grades in the overall sample (n = 4,600). A multiple-group mediation model suggested that these effects did not significantly differ across students with EBR and UBR, though the mediation estimates were smaller in magnitude and not statistically significant among students with EBR. Implications for the role of parental monitoring as an intervention target within a multitiered system of support for social and behavioral skills in middle school, as well as limitations and future directions are discussed.