Background: Academic buoyancy is students' ability to successfully deal with setbacks and challenges that are typical of academic life. The present study extends previous preliminary cross-sectional work that tentatively identified five motivational predictors of academic buoyancy--referred to as the "5Cs" of academic buoyancy: confidence (self-efficacy), coordination (planning), commitment (persistence), composure (low anxiety), and control (low uncertain control). Aims: The study seeks to more clearly ascertain the effects of motivation (and its mediating role) on academic buoyancy over and above prior academic buoyancy. Sample: The study comprised N=1,866 high school students from six schools. Method: Longitudinal data were collected (1 year apart) and the hypothesized model exploring longitudinal effects was tested using structural equation modelling. Results: After controlling for prior variance in academic buoyancy, the 5Cs were significant predictors of subsequent academic buoyancy. Furthermore, over and above the direct effects of prior academic buoyancy on subsequent academic buoyancy, the 5Cs significantly mediated this relationship. Conclusions: The study concludes with a discussion of the substantive, applied, and methodological implications for researchers and practitioners seeking to investigate and address the academic buoyancy of students who require the capacity to effectively function in an ever-challenging school environment.