Harter, Waters, and Whitesell (1998) demonstrated that adolescents possess differentiated evaluations of self-worth across various interpersonal contexts. If this differentiation also occurs with more specific self-perceptions, such as perceived sport competence, this approach may further our understanding of athletes' achievement-related strivings. The purpose of this study was to examine whether athletes possess distinct self-perceptions of sport competence across various interpersonal contexts, and if so, to describe the nature of this intraindividual variability. Male and female college athletes (N=170) completed questionnaires assessing: (a) their beliefs about their ability in sport when interacting with their mothers, fathers, coaches, teammates, and other students, respectively (relational self-perception; RSP), (b) the athletes' beliefs about how each of these significant others view their ability (reflected appraisal; RA), and their (c) generalized self-perceptions of sport competence, enjoyment and sport commitment. Various analyses provided evidence for the differentiation of athletes' RSPs. First, a principal axis factor analysis on the RSP measure revealed 3 factors labeled: (a) RSP - parents, which reflected a combination of the athletes' self-perceptions of sport competence in the contexts of their mother and father, (b) RSP - sport-others, which reflected a combination of the coaches and teammates interpersonal context, and (c) RSP - students, which reflected the interpersonal context of other students. Further supporting this distinction, correlations between the RSP and the RA within a corresponding interpersonal context were systematically higher than the correlations between a specific RSP and the non-corresponding RAs. Descriptive analyses showed athletes held significantly (p < .01) less positive RSPs in the context of sport-others (M=3.88, SD=.58, on a 5-point scale) relative to parents (M=4.23, SD=.55) and other students (M=4.26, SD=.58). There were, however, considerable interindividual differences in the intraindividual variability of these self-perceptions. While 23.5% of the athletes reported no differences in their self-perceptions across the three interpersonal contexts, 76.5% reported at least some variability, with an average absolute difference of .56 (SD=.37). Multiple regression and cluster analyses revealed differences in the relative importance of the athletes' RSPs, with RSP - sport-others demonstrating the strongest association with generalized self-perceptions of sport competence, enjoyment, and commitment, whereas RSP - students demonstrated little association with these achievement-related constructs. Results are discussed in terms of understanding the self and achievement-related outcomes in sport.