Self-determination theory postulates various types of motivation can be placed on a continuum according to their level of relative autonomy, or self-determination. We analyze this question through the application of a bifactor-ESEM framework to the Academic Motivation Scale, completed by undergraduate (N=547; Study 1) and graduate (N=571; Study 2) students. In both studies, the results showed that bifactor-ESEM was well-suited to modeling the continuum of academic motivation, and provided a simultaneous assessment of the global level of self-determination and of the specific motivation factors. Global academic self-determination positively predicted satisfaction with studies and vitality. It also negatively predicted dropout intentions and ill-being. Specific motivation types additionally predicted outcomes over and above the global factor.