Students perform better in school to the extent they are able to engage fully, cope adaptively, and bounce back from obstacles and setbacks in their academic work. These three processes, which studies suggest are positively inter-connected, may comprise a self-sustaining system that enables "motivational resilience." Using self-determination theory to frame hypotheses about such a motivational system, this study examined (1) whether a set of personal factors (self-perceptions of relatedness, competence, and autonomy), interpersonal resources (perceptions of teacher warmth, structure, and autonomy support), and emotional reactivity predicted changes in motivational resilience over the school year; (2) whether motivational resilience in turn predicted improvements in students' achievement and also fed back to increases in their personal and interpersonal resources; and (3) whether teacher support could shift established motivational patterns. A latent path model depicting these processes showed a good fit with self-report data from 1,020 students in Grades 3 through 6 collected in fall and spring of the same school year (including achievement data from a random subset, n = 365). Multiple regressions predicting changes from fall to spring refined the proposed model. Moreover, teacher support was crucial: Students who began the year with at-risk profiles, but also experienced high teacher support, ended the year on par with low-risk students; whereas students who began with resilient profiles but experienced low levels of teacher support ended the year at-risk. Discussion focused on identifying levers for intervention and the essential role teacher support plays in these dynamics.