Background: The literature on motivation suggests that student learning and performance is influenced by the motivational climate, and that positive benefits can be derived from exposure to a mastery motivational climate. Nonetheless, to date, only a few studies have attempted to investigate a mastery motivational climate in a naturalistic setting with young children. Purpose: To examine the influence of a mastery motivational climate intervention on children's motor skill performance in a naturalistic setting, with the hypothesis that children exposed to the mastery motivational climate physical education intervention would achieve greater improvement in motor skill development than students who experienced a low autonomy climate physical education intervention. Participants and setting: 64 kindergarten children at two separate schools in the rural south of the USA. Research design: A pretest-posttest quasi-experimental design was used due to the lack of random assignment of participants to groups. Intact classes at two schools were assigned to group. Each motor skill program consisted of 30, 30-minute lessons during a six-week period. Data collection: Fundamental motor skill performance was measured using Ulrich's Test of Gross Motor Development (TGMD-2). The TGMD-2 was administered three separate times: first, at the beginning of the school year (Pretest 1), second, after six weeks of school just prior to the intervention (Pretest 2), and finally, at the end of the six-week intervention period (Posttest). Data analysis: Two separate 2 x 2 (Group x Time) ANOVAs with repeated measures on the last factor were used to determine if children exposed to the motor skill interventions experienced significant positive changes in motor skill performance on the TGMD-2 sub-scales for locomotor and object control motor skills. Findings: Results indicated significant Group x Time interactions for the locomotor sub-scale (p = 0.001) and the object control sub-scale (p = 0.001). The mastery group improved significantly from pre- to post-intervention for locomotor and object control skills, while the low-autonomy group did not. Conclusions: The results provide evidence that a mastery motivational climate can have a positive impact on children's fundamental motor skill performance and suggest that even young children who are in the initial stages of motor skill performance can benefit from a self-directed climate. (Contains 2 figures and 4 tables.)