Using achievement goal theory and the expectancy-value model of achievement choice as theoretical frameworks, this study examined relationships between parents beliefs and their childrens motivation in an elementary physical education running program. Participants included 102 parents and their children (49 boys; 53 girls) in the third and fourth grades. The parents completed questionnaires assessing their achievement goals, competence beliefs, task values, and gender stereotypic beliefs about running. Childrens persistence/effort was assessed by the number of laps run/walked over the year-long running program. Performance was measured by the timed mile run. Results indicated that only parents competence/value beliefs were predictive of their childrens persistence/effort and mile run performance. Gender stereotypic beliefs influenced achievement goals the parents adopted for their children. Findings provided empirical support for the importance of parental beliefs for childrens motivation in physical activity.