Teaching students social values has long been associated with K-12 education (Solomon, Watson, Delucchi, Schaps, 1988). Violence, bullying, and other anti social behaviors are some of the greatest concerns of those that educate our youth. Public school teachers consistently cite discipline and management as one of their foremost concerns each day as they engage in instruction (Manning & Bucher, 2005). Practitioners and scholars are re-focusing their attention on implementing and empirically documenting social development programs (Hellison, 2003; Martinek & Hellison, 1998; Solomon, Watson, Battistich, Schaps, & Delucchi, 1996; Shields & Bredemeier, 1995; DeBusk & Hellison, 1989). The context of physical education, due to it's naturally interactive and conflict oriented environment may be an ideal setting for social skill development. Although widely used but lacking empirical support, the personal responsibility model encourages students to apply positive social behavior through such activities as group discussion, goal setting and reflection (Hellison, 2003; Hellison & Walsh, 2002). The present research study examined the effects of Hellison's personal responsibility model on individual and class wide anti and positive social behavior. A multiple baseline, behavior analytic design was used to best determine the effects of the intervention on the students. Three students were chosen as participants based on the observed persistence of anti social behavior. Results indicated a positive effect on the individual students in the reduction of socially and personally irresponsible behavior. In addition, data from all three students illustrated increases in the amount of time the students were fully participating without direct teacher supervision (self direction). Data also showed similar increases in caring types of behaviors. In addition, the Child Social Behavior Questionnaire (CSBQ) developed by Warden and colleagues (Warden, Cheyne, Christie, & Reid, 2003) was also administered to determine the effects of the model on whole class pro and anti social behaviors in which the intervention was implemented and a control site in which no intervention was conducted. The questionnaire was administered both pre and post intervention at both schools. Statistically significant difference were found between the two schools, with the school that utilized the model indicating improvements in whole class pro social behavior and reductions in anti social behavior (p<.01). This study is the first to demonstrate empirical evidence of the positive effects of Hellison's personal responsibility model on individual and whole class social behavior in a physical education setting.Keyword(s): middle school issues, physical education PK-12, violence/prevention