This study examines adolescent accounts of group rejections, as well as regrets regarding the failure to utter disagreement with the social exclusion of others. Six reasons for not voicing disagreement are identified: group dynamics, social fears, uncertainty, social inadequacies, qualities of the excluded individual, and low motivation. A model is proposed that describes the negative social reasoning by group members who remain silent when others are rejected, and intervention strategies that advance prosocial group inclusion are presented. Although successful entry into childhood peer groups is a prerequisite for development of self-concept, social skills, and school successes, little is known about real-world attempts to penetrate social group boundaries. The authors collected more than 600 adolescent accounts of group rejections, as well as regrets concerning the failure to voice disagreement. Narrative accounts revealed six reasons for failing to voice disagreement with the social exclusion of others: (a) group dynamics, (b) social fears, (c) uncertainty, (d) social inadequacies,(e) qualities of the excluded individual, and (f) low motivation. Seventy percent of these adolescents shared specific language they now regretted not using at the time. Two cognitive frameworks emerged: (a) group membership was perceived as fragile and (b) rejection stigma was perceived as contagious. A model describing negative social reasoning used by those who remain silent during the rejection of others is offered, as well as intervention strategies to stimulate prosocial group inclusion