According to self-determination theory, motivation is multidimensional, with motivation regulations lying along a continuum of self-determination (Ryan & Deci, 2007). Motivation regulations associate with important affective and behavioral outcomes both within and outside of physical activity settings such as physical education. However, there is little longitudinal data examining changes in motivation regulations, especially during the entry into and through middle school. This study used multilevel modeling (MLM) to identify changes in motivation regulations and predictors of change for students into and across the transition to middle school. Students (N = 353) in physical education classes completed questionnaires of psychological need variables, mastery climate, teacher support, and motivation regulations during the spring semester for three consecutive years starting in either fifth or sixth grade. Results demonstrate normative decreases in perceptions of competence (γ = −0.06, p < .01), relatedness (γ = −0.08, p < .05), mastery climate (γ = −0.28, p < .01), teacher support, (γ = −0.18, p < .01), intrinsic motivation (γ = −0.09, p < .01) and identified regulation (γ = −0.09, p < .01) and increases in external regulation (γ = 0.10, p < .01). Demographic and theoretical predictors were tested to explain between-student variability in intercepts and linear change. Psychological need satisfaction, mastery climate, and teacher support predicted (p < .05) motivation regulation change consistent with theory and/or research. Adaptive social contextual perceptions and perceptions of competence and relatedness are linked with adaptive motivational trajectories in a U.S. middle school sample.