What are the factors that motivate children to do well in physical education running programs? Do boys and girls differ in motivation and performance in those running programs? Understanding such issues may help physical education teachers design better running programs where boys and girls are equally motivated to participate in and benefit from regular running. In earlier studies we found that children who valued a running program were more likely to continue a running program in the future. We also found that parental belief in the value of the running program also contributed to continued participation. Finally, we noted that boys and girls did not differ on mean scores of the motivational variables as well as the mile run. However, since we only measured children’s motivation at one point in time, our ability to examine how their motivation might change over time was limited. Therefore, this study was to examine children's motivational changes as a result of participation in a year-long running program. Participants were fourth graders (N=119; 67 boys and 52 girls). In the fall and spring of the school year, they completed questionnaires on 5-point scales assessing achievement goals, expectancy-related beliefs (ERBs), subjective task values (STVs), and intention for future participation in running. Children also completed a timed mile run as an assessment of cardiovascular endurance. A repeated measures multivariate analysis of variance yielded a significant main effect for time (p < .001). There was no significant main effect for gender and the interaction between time and gender. Follow-up univariate tests indicated that the mean level of children’s task- and ego-involved goals, STVs, and intention for future participation in running decreased over time. The mean level of children’s avoidance goal and ERBs, however, remained the same over time. The children also improved their mile run times over the course of the program. Multiple regression analyses indicated that STVs were predictive of children’s intention for future participation in running and ERBs were predictive of children’s mile run over time. In sum, children’s running times improved but their motivation declined while participating in a year-long running program. Further study is now needed to identify and examine potential causes for the decline in motivation. Qualitative measures including interviews with students, teachers, and parents could prove helpful in unearthing underlying reasons. Such information may be beneficial to teachers and their efforts to maintain children's motivational levels in physical education.