This study seeks to find out what kind of effects small- group art therapy has on the social skill development of children with developmental disability This research is to verify the small group art therapy program for social skill improvement of children with development disorders and studied one male and female child each from May to December 2011 for 28 rounds of sessions. Test tools were Gresham & Elliott’s Social Skills Rating System (SSRS) (1987) and compared change results before and after the therapy program. The findings are as follows: First, small group art therapy activities were found to have positive effects on the cooperation skill improvement of children with developmental disability Second, small group art therapy activities were found to have positive effects on the self-assertion skill improvement of children with developmental disability. Third, small group art therapy activities were found to have positive effects on the self-control skill improvement of children with developmental disability.