Background. Contemporary research conducted in the context of school physical education (PE) has increasingly embraced various tenets of self-determination theory (Deci & Ryan, 1985, 1991). Despite this increase in research attention, some postulates of the framework remain unexplored (e.g. impact of a need-supportive climate). As such, the present study sought to provide a more comprehensive test of self-determination theory. The present work also examined Deci and Ryan's claim that the motivational sequence embraced by their framework is invariant across gender. Aims. (i) To examine a model of motivation based on the tenets of self-determination theory, and (ii) explore the invariance of the model across gender. Sample. Participants were 950 British secondary school students (443 male, 490 female, 17 gender not specified) Method. Participants completed a questionnaire that included measures of need support, need satisfaction, motivation, positive and negative affect, task challenge, and concentration. Results. Structural equation modelling (SEM) analysis revealed that students who perceived a need-supporting environment experienced greater levels of need satisfaction. Need satisfaction predicted intrinsic motivation, which, in turn, linked to adaptive PE-related outcomes. In contrast, need satisfaction negatively predicted amotivation, which, in turn, was positively predictive of feelings of unhappiness. Multi-sample SEM invariance testing revealed the model to be largely invariant for male and female students. Conclusions. The results of the study provide support for self-determination theory and corroborate the application of the framework to the context of school PE. Further, we largely found support for the invariance of the motivational processes embraced by self-determination theory across gender.