The purpose of this paper is to examine the features of identity formation in college athletes from the viewpoints of ego development and identification with a sport. In study 1, athletes' identity was defined operationally as "the subjective sense and consciousness as an athlete" and "the psychological attitude of self definition through the sports experience." A scale for assessing athletes' identity (athletes' identity scale) was established. In study 2,356 male college athletes were rated with both the athletes' identity scale and Loevinger's (1970) sentence completion test for assessing ego development. Considering the distribution of scale scores, 40 Ss representing high and low scores on both scales were interviewed and the interviews were rated by 3 judges using Marcia's (1964) procedure for determining identity status. The 40 Ss were also interviewed using an interview manual of involvement in athletic sports. It was clarified that high athletes' identity levels were associated with the foreclosure. The formation of ego identity through althletes' identity seems to lead to the attainment of identity without crises. It is considered that for college athletes, exploring ego identity formation is made passive by a high athlete's identity. High levels of ego development with low levels of athletes' identity is associated with the statuses in which crises are a common feature (achievement and moratorium). It is considered that levels of athletes' identity imply the opportunity for identity formation. It is suggested that high levels of ego development are necessary for identity achievement. High levels of ego development are also associated with subjective involvement in athletics. According to this result, it can be considered that subjective involvement in athletics has a desirable effect on ego identity formation.