This investigation utilized a contrived play group procedure to examine the behavioral patterns leading to chronic victimization by peers in middle childhood. 30 play groups, each of which consisted of 6 unacquainted African-American 6-year-old or 8-year-old boys, met for 45-min sessions on 5 consecutive days. Play group interactions were videotaped and then examined. 13 boys who came to be chronically victimized by their play group peers were identified, along with matched nonvictim contrasts. Victims demonstrated lower rates of assertive behaviors, such as persuasion attempts and social conversation initiatives, and higher rates of nonassertive behaviors, such as submissions to peers' social initiatives, than contrasts. This nonassertive behavior pattern appears to have preceded the development of chronic victimization. Children who eventually emerged as victims were pervasively submissive, beginning in the initial 2 sessions. However, marked individual differences in victimization by peers did not become apparent until the final 3 sessions. These data provide evidence of strong linkages between submissive social behavior and the emergence of chronic victimization by peers.