Higher levels of parenting stress and lower levels of parental competency have been shown to adversely affect a variety of child outcomes such as both externalizing and internalizing behavior problems. Behavioral parent training programs simultaneously decrease parenting stress while increasing parental competency. Recent research has focused on possible mechanisms of change that influence the efficacy of behavioral parent training programs. The present study examined parental competency, specifically parental efficacy and satisfaction, as mechanisms of change in the relationship between attendance in the Parenting Our Children to Excellence (PACE) program and long-term levels of parenting stress. Six hundred and ten parents participated in the PACE parenting program and measures were collected at pre-treatment, post-treatment, and follow-up. Path analysis was utilized to test parental competency as a mediator between engagement in PACE and follow-up parenting stress. Parental satisfaction, one factor of parental competency, was found to be a significant mediator between engagement in PACE and follow-up parenting stress. This study has important implications in further identifying mechanisms of change within behavioral parent training programs.