Objectives: To investigate the sequence of relations between dimensions of perfectionism, autonomous and controlled motivation, and coping (Study 1) or exerted effort (Study 2) during training. Design: Cross-sectional (Study 1), short-term longitudinal (Study 2). Methods: In Study 1, participants were 333 Greek adolescent athletes (M age = 15.59 years, SD = 2.37) from various sports; they were assessed with respect to their dimensions of perfectionism, perceived competence, self-determined motivation, and sport-related coping skills. In Study 2, participants were 63 adolescent athletes (M age = 14.40 years, SD = 1.58) participating in a three-week summer basketball camp; they first were assessed with respect to their perfectionism, perceived competence, and self-determined motivation and then, for consecutive times after daily training, with respect to their situational self-determined motivation and the effort they invest during training. Results: In both studies, structural equation modeling revealed that personal standards were positively related to both autonomous and controlled motivation and that concern over mistakes were uniquely related to controlled motivation. In turn, autonomous motivation, as compared to controlled motivation, was linked with better coping (Study1) and more effort (Study 2). Conclusion: Athletes with high personal standards are more likely to report effective coping or to put more effort if they become (or remain) autonomously motivated. In contrast, athletes with concerns over mistakes are more likely to exhibit controlled motivation and, in turn, to report poorer coping skills or to put less effort compared to autonomous motivated athletes. (C) 2011 Elsevier Ltd. All rights reserved.