Growth and maturation impact the development of young athletes’ physique and function. It is likely that psychological and behavioral characteristics will also be impacted by maturity status. Perceived collective efficacy (CE) is a potential mediator of sports performance and may be influenciated by maturity status. Therefore, this study examined the perceived CE variation between young basketball players accounting for the influence of chronological age and biological maturity status. The sample included 57 adolescent basketball players aged 9.5 to 15.5 years. Chronological age, estimated age at peak height velocity (PHV) and CE through the Portuguese version of the Collective Efficacy Questionnaire for Sports were considered. Bayesian multilevel modeling was used to examine athletes’ perceived CE dimensions variation by maturity status and age. Overall, the adolescent basketball players’ perceived CE scores were high for all dimensions: ability (8.77±1.15); effort (9.20±1.03); persistence (8.87±1.18); preparation (8.96±1.08); unity (8.88±1.22). The variability estimates were very large, suggesting that the influence of maturity status on variation may be residual. There was no substantial relation between chronological age and the variation scores, although the results suggest that perceived variation was independent of chronological age variation and between players variation in maturity status. Further study examining the relations of growth, functional performance development, and perceived CE would be relevant for the holistic understanding of young basketball players’ development. Growth and maturation impact the development of young athletes’ physique and function. It is likely that psychological and behavioral characteristics will also be impacted by maturity status. Perceived collective efficacy (CE) is a potential mediator of sports performance and may be influenciated by maturity status. Therefore, this study examined the perceived CE variation between young basketball players accounting for the influence of chronological age and biological maturity status. The sample included 57 adolescent basketball players aged 9.5 to 15.5 years. Chronological age, estimated age at peak height velocity (PHV) and CE through the Portuguese version of the Collective Efficacy Questionnaire for Sports were considered. Bayesian multilevel modeling was used to examine athletes’ perceived CE dimensions variation by maturity status and age. Overall, the adolescent basketball players’ perceived CE scores were high for all dimensions: ability (8.77±1.15); effort (9.20±1.03); persistence (8.87±1.18); preparation (8.96±1.08); unity (8.88±1.22). The variability estimates were very large, suggesting that the influence of maturity status on variation may be residual. There was no substantial relation between chronological age and the variation scores, although the results suggest that perceived variation was independent of chronological age variation and between players variation in maturity status. Further study examining the relations of growth, functional performance development, and perceived CE would be relevant for the holistic understanding of young basketball players’ development.