The purpose of the present study was to examine the effects of chum formation in preadolescence on women's ego development. 76 girls in the sixth grade as subjects have been tested using methods such as the Mannarino's chumchecklist, the author's intimacy motive scale, and the prospective adolescent crisis state scale. In addition, 93 senior high school girls, have completed the retrospective preadolescent chumchecklist and the adolescent crisis state scale (Nagao 1989). And also, 63 middle-aged women had been asked to answer questions based upon the middle-aged crisis scale (Nagao 1990), the retrospective adolescent crisis state scale, and the retrospective preadolescent chumchecklist. The main results were as follows: (1) The existence of chum in preadolescence had a stronger effect on the future ego development than the degree of the intimacy motive, and also (2) had more influence on the adolescent crisis state than on the middle-aged crisis state.(3) The former crisis state was connected with the latter crisis state and (4) the degree of the adolescent crisis state prospected by the preadolescent girls was stronger than that retrospected by the middle-aged women.