Development of achievement-related motives in young athletes is believed to be influenced by the motivational climate created by coaches. In a longitudinal multilevel design utilizing 47 youth basketball teams, coach-initiated motivational climate was used to predict changes in 9–13 year old athletes' achievement goal orientations over the course of a season. Mastery climate scores on the Motivational Climate Scale for Youth Sports were associated with significant increases in mastery goal orientation and decreases in ego orientation scores on the Achievement Goal Scale for Youth Sports. Ego motivational climate scores were significantly related to increases in ego goal orientation scores. These relations were not influenced by athletes' age or gender. Intraclass correlations indicated low within-team consensus in athletes' motivational climate scores, suggesting an individual-rather than team-level perceptual construct. These and other findings indicate that achievement goal orientation research can be extended downward to children below the age of 11.