The joint development of trajectories of bullying perpetration and peer victimization from Grade 5 to Grade 8 and concurrent and predictive associations with parent- and child-reported symptoms of psychopathology (anxiety, depression, attention-deficit/hyperactivity disorder, and somatization) were examined in a large sample (N = 695) of Canadian children. Dual trajectory modeling revealed four distinct subgroups of children: (a) those low in both bullying perpetration and peer victimization (low/limited involvement); (b) those with moderately increasing levels of involvement in bullying perpetration and low levels of victimization (bullies); (c) those with low levels of bullying perpetration and moderate/decreasing levels of peer victimization (initial/declining victims); and (d) a victim-to-bully group characterized by increasing bullying perpetration and moderate decreasing victimization. Conditional probability results suggest that a pathway from peer victimization to involvement in bullying is more likely than a pathway from bullying perpetration to peer victimization. Children classified in the victim-to-bully and initial/declining victim groups showed more pervasive elevations in parent- and child-reported symptoms of psychopathology across elementary and middle school and in Grade 9 than individuals with limited involvement in bullying or peer victimization. Most associations with Grade 9 parent-and child-reported symptoms of psychopathology remained even after controlling for initial symptoms of psychopathology. Results are discussed in the context of extant taxonomies of involvement in bullying, the temporal relationship between bullying and victimization, and the increased mental health risk associated with both pure victims and bully-victims.