This study was carried out to evaluate the effects of Sociability Promotion Program on the peer relation and loneliness of child-psychiatric inpatients. The subjects of this study were 9 inpatients at child-psychiatry unit in S university hospital, 2 schoolers and 7 adolescents. The interventional activity consisted of playful seession structured to have intensive social interactions, such as introduction, relaxation, cooperation, assertive skills, physical contact, and evaluation. Data were collected before and after the program by using self-report questionnaire for peer relation and loneliness and direct observation and audio-taping method for activity evaluation. The data were analyzed with Wilcoxon signed Rank Test and Content Analysis. The results obtained were as follows : There was a significant difference between the score on peer relation(p＜.05) and loneliness(p＜.10) of the subjects through the program. After the program, the peer relation of the subjects became more positive than before and the score of the loneliness decreased. Although it showed positive change, the mean score was still a problematic level. And they were different individualiy, the half of the subjects changed positively, whereas the other half did not. Especially the subjects who had serious problems in peer relation changed much more. However, there were two cases with negative progress, due to changes in medication and his competitive characters. Even the subjects who had no changes statistically became more relaxed and more responsive. Also they became more assertive, more expressive, and appropriately defensive. Before the program, they could not complete sentences, pay attention and give positive feedback to others. But in the group process their voices have turned out louder and their interrupting behaviors have been less frequent. The subjects evaluated that they acquainted with their peer, joyful experience, chances to express themselves, became assertive, sociable and cooperative with others through this program. But they evaluated it was rather difficult to deal with uncomfortable physical environment, speedy procedure, unfamiliar contents of activity, physical contacts, etc. It needs some modifications on this program are required to be applied for the inpatients. In conclusion, Sociability Promotion Program was effective to promote peer relation, social behaviors, and decreasing loneliness. Thus with some modifications on this program can be recommended as a nursing intervention for inpatients with social problems.