Objective: The aim was effect deliberate practice and deliberate play on sports skills with emphasis on specialization and diversification in boys 10-12. Methods: The 120 male students randomly divided into four groups of volleyball, soccer, basketball deliberate practice and deliberate play. Pretest and posttest were AAHPERD volleyball, soccer, and Basketball sports skills. Duration of the project was 16 weeks and 3 sessions per week and 90 minutes each session began. Data obtained from questionnaires and personal details about sports experience and test were adjusted using parametric tests, such as T-dependent test and MANOVA with Tukey post hoc test, and software Statistical SPSS19. Results: The results of the study showed that compared four groups, deliberate plays to other deliberate practices have a better motor skill in volleyball, soccer and Basketball sports skills (P<0.05). Volleyball and soccer deliberate practice group had developed Soccer Dribble Test and Control dribble and Defensive movement basketball skills test. Basketball deliberate practice group had not developed the others soccer and volleyball skills. Conclusion: The results showed that diversification participation in some exercises during the early stages of growth, can facilitate the development of general cognitive and physiological skills and create a rich environment for children.