Stressful situations are linked to both individual and environmental characteristics. Specific populations, who have to face repeated stressful events might be able to develop specific strategies or may be at risk regarding health issues. The analysis of their coping capacities implies to understand different psychological constructs related to psychological adjustment. Currently, from a theoretical and empirical point of view, two concepts give best the account of psychological adjustment: coping strategies (CS) and defense mechanisms (DM) (Cramer, 1998). It should be determined whether coping strategies and defense mechanisms predict the adaptation. The main goal of this study is to better understand the relationships between these two psychological constructs in a specific stressful situation: sport competition. The objectives were to examine the adequacy of the traditional distinction based on the adaptative or maladaptative characteristics of each process and to investigate its contribution in the prediction of performance adjustment. 36 French international athletes from 15 to 18 years of age (M =16.5, SD =1.93), participated in this study. They answered two questionnaires : the Defense Style Questionnaire (DSQ) purports to assess individual's conscious derivatives of DM (Andrews et al., 1993), and the Ways of Coping Questionnaire (WOCQ, Folkman & Lazarus, 1988) assessed CS applicable in numerous stressful settings. The index performance (IP) was the performance indicator used for this study. IP scores were obtained for each participant by subtracting standard performance from the time performance realized during the competition. Correlations between performance adjustment, CS and DM indicated that among the six factors, (1) mature defenses and seeking social support (r = .52), (2) immature defenses and distancing / avoidance (r = .44) were significantly correlated. Concerning the contribution of CS and DM in prediction of performance adjustment, multiple regression analyses were performed. Mature defenses, problem solving and distancing/avoidance were significant predictors of performance adjustment. R² = .57, F(6,19)=6,4954, p<.05 The results reveal that both CS and DM are related to performance adjustment. The classical view based on adaptive CS and maladaptive DM is not supported. Both concepts are involved in psychological adaptation process and have both their specificity and their shared characteristics. Further studies should investigate the respective role of CS and DM in adaptation in order to better understand the differences and similarities between these two concepts related to specific situations and different stressors.