Research literature has suggested that teachers instruct students to believe that exerting effort can improve ability and performance (Dweck, 1999; Xiang, Lee, & Williamson, 2001). Understanding the value of effort can motivate students to strive for success when encountering difficulty (Dweck, 1999). Little research, however, has been conducted to investigate the individual differences in understanding the meaning of effort. Individuals' characteristics such as ability conceptions (Dweck, 1999) can have a great impact on their understanding the meaning of effort. It has been suggested that when compared to participants who viewed ability as fixed, those with incremental views of ability would be likely to endorse more of the view that working hard allows them to fully use their ability. Some children with fixed veiws of ability, however, would still believe in the efficacy of effort. Findings from this line of research have the potential to guide teachers to design individualized instruction to enhance students' motivation and learning. The purpose of this study, therefore, was to investigate individuals' understanding of the meaning of effort in the ability conceptions framework. This study was part of a larger project. Participants were 79 students in 8th grades enrolled in coeducational physical education classes from a Southeast university lab school. They practiced a novel task called Lunastix and completed the ability conception questionnaire prior to instruction and the meaning of effort survey after practicing the task. Chi-square tests for one-way table were conducted to examine whether the proportions of participants' agreement and disagreement with the meaning of effort statements were equal. Logistic regressions with a descending option were used to examine the relationship between ability conceptions and understanding of the meaning of effort. Consistent with the literature, the results of this study suggest that the majority of the participants believed in the efficacy of effort regardless of what view of ability they endorsed. Participants with stronger incremental views of ability, however, were likely to endorse more of the view that trying hard allowed them to fully use their ability. For those who expressed entity views of ability, they tended to believe that high effort leads to low ability. Some children still believed in the efficacy of effort even though they believed that ability is fixed. To promote active engagement and enhance skill learning teachers capitalize on the belief in the efficacy of effort by focusing their motivational strategies on students' effort and creating a task-involved climate. Keyword(s): middle school issues, physical activity, student issues