A study tested self-determination theory (SDT) in school physical education (PE), examining how need-supportive environments influence student motivation and outcomes. The research involved 950 British secondary students, with 443 males, 490 females, and 17 gender unspecified. Participants completed a questionnaire assessing need support, satisfaction, motivation, affect, task challenge, and concentration. Structural equation modeling (SEM) revealed that students in need-supportive environments experienced higher need satisfaction, which predicted intrinsic motivation and adaptive PE outcomes. Need satisfaction also negatively predicted amotivation and feelings of unhappiness. Multisample SEM invariance testing showed the model was largely invariant across genders. The study supported SDT, confirming its applicability to PE and finding support for the invariance of motivational processes across gender. SDT posits that intrinsic motivation, various types of extrinsic motivation, and amotivation lie on a continuum of self-determination. The study found that need satisfaction positively predicted intrinsic motivation and identified regulation, while negatively predicting external regulation and amotivation. The results suggest that fostering need-supportive environments in PE can enhance intrinsic motivation and positive outcomes. The study also highlighted the importance of teacher-created social contexts that promote need satisfaction, autonomous motivation, and adaptive responses. Future research should explore the effects of multiple social agents and consider objective measures of physical activity to better understand the factors influencing student perceptions of the social context in PE. The findings emphasize the importance of promoting autonomy, competence, and relatedness in PE to foster intrinsic motivation and positive engagement. The study also noted that amotivation negatively predicted concentration and feelings of unhappiness, while external regulation showed no significant associations with the dependent variables. The results indicated that the model fit was largely invariant across gender, with some differences in the path between need satisfaction and introjected regulation. Overall, the study supports SDT and highlights the importance of creating need-supportive environments in PE to enhance student motivation and well-being.A study tested self-determination theory (SDT) in school physical education (PE), examining how need-supportive environments influence student motivation and outcomes. The research involved 950 British secondary students, with 443 males, 490 females, and 17 gender unspecified. Participants completed a questionnaire assessing need support, satisfaction, motivation, affect, task challenge, and concentration. Structural equation modeling (SEM) revealed that students in need-supportive environments experienced higher need satisfaction, which predicted intrinsic motivation and adaptive PE outcomes. Need satisfaction also negatively predicted amotivation and feelings of unhappiness. Multisample SEM invariance testing showed the model was largely invariant across genders. The study supported SDT, confirming its applicability to PE and finding support for the invariance of motivational processes across gender. SDT posits that intrinsic motivation, various types of extrinsic motivation, and amotivation lie on a continuum of self-determination. The study found that need satisfaction positively predicted intrinsic motivation and identified regulation, while negatively predicting external regulation and amotivation. The results suggest that fostering need-supportive environments in PE can enhance intrinsic motivation and positive outcomes. The study also highlighted the importance of teacher-created social contexts that promote need satisfaction, autonomous motivation, and adaptive responses. Future research should explore the effects of multiple social agents and consider objective measures of physical activity to better understand the factors influencing student perceptions of the social context in PE. The findings emphasize the importance of promoting autonomy, competence, and relatedness in PE to foster intrinsic motivation and positive engagement. The study also noted that amotivation negatively predicted concentration and feelings of unhappiness, while external regulation showed no significant associations with the dependent variables. The results indicated that the model fit was largely invariant across gender, with some differences in the path between need satisfaction and introjected regulation. Overall, the study supports SDT and highlights the importance of creating need-supportive environments in PE to enhance student motivation and well-being.