The current study combines models about the effects of peer victimization on negative self-cognitions with models about the effects of negative cognitions on suicidal ideation. In a two-wave longitudinal investigation of high schoolers (N = 192) and college students (N = 142), the study examined perceived burdensomeness, thwarted belongingness, and hopelessness as mediators of the prospective relation between peer victimization and suicidal ideation. Path analyses yielded three findings: (a) peer victimization predicted perceived burdensomeness but not thwarted belongingness or hopelessness; (b) perceived burdensomeness, thwarted belongingness, and hopelessness each predicted suicidal ideation; and (c) perceived burdensomeness mediated part of the relation between peer victimization and suicidal ideation. These patterns were consistent across samples and did not differ significantly by gender. Results are consistent with aspects of all three original models and provide support for a new cognitive mediation model regarding the relation of peer victimization to suicidal ideation.