The present study was based on the theoretical postion that interpersonal problem solving skills vare independent of impersonal ones. The purposes of this study were: 1) to analyze developmental changes of interpersonal cognitive problem solving skills of six, eight, and ten year-old children 2) to investigate whether there is a qualitative difference in interpersonal cognitive problem solving skills according to the kinds of the interpersonal task, and 3) to determine the correlation of interpersonal cognitive problem solving skills with children’s popularity. Three hundreds children of 2 kindergartens and 2 elementary schools and their 300 mothers in Inchon City were tested. Two instruments were used. First, the Interpersonal Cognitive Problem Solving Test, which consisted of 4 sub-categories; alternative thinking, consequential thinking, causal thinking and means-ends thinking. Secondly the Sociometric measurement. Multivariate analysis of variance, multi-response analysis, repeated measurement method and Pearson’s correlation coefficients were employed for statistical treatment. The major findings were as follows : (1) Chidren’s interpersonal cognitive problem solving skill, when applied to Selman’s model, showed, the typical tendency of undifferentiated/egoentric and differentiated/ subjective thinking at 6 years, differentiated/subjective and self-reflective/reciprocal thinking at 8 years, and self-reflective/reciprocal and mutual thinking at 10 years. The most children, however, had the ‘request’ scheme of differentiated/subjective thinking positively and many children took the ‘fair’ and ‘ waiting’ scheme of mutual thinking positively. These seem to mean a high level of interpersonal cognitive problem solving skills have been built up even in early childhood. (2) When the children tried to solve the interpersonal problem positively, 3 interpersonal problems showed similar V pattern (i. e., subjective, mutual, self-reflective thinking in the hierarchy of response frequency). On the other hand, in their negative problem solving thinking, the tendency was egocentric thinking in mother problem, subjective thinking in peer problem, mutual thinking in teacher problem. (3) Interpersonal cognitive problem solving skills showed the positive correlation with children’s popularity. (4) Interpersonal cognitive problem solving skills made differences in accordance with the parent’s socio-economic status and education.