This study examined the role of motivational factors on the academic achievement of children in the 3rd, 4th, and 5th grades. Four motivational factors were assessed: the child's motivational attributions, motivational goal orientation, self-perception, and mastery-oriented behaviors in the classroom. Mastery-oriented behaviors include being goal-oriented, being able to work independently, seeking out challenging tasks, and participating as an active agent in the learning process. Results of parent, teacher, and child measures indicated that intrinsically goal-oriented children tended to have high academic self-concepts, exhibited high levels of mastery behaviors in the classroom, and scored well on school achievement tests. Achievement levels were found to be a joint result of ability and motivation, and mastery behaviors in the classroom were the link between intrinsic goal orientation and achievement, and between self-concept in the classroom and achievement. The behavioral measure of children's mastery was the most important indicator of achievement. When judgments of the children's abilities were taken from classroom teachers and from parents, it was found that teachers views were more highly associated with achievement levels. Recommendations for teachers based on the study results include allowing students to have choices between equally challenging tasks, and minimizing external rewards as motivators for achievement. (JPB)