The main purpose of this study was to investigate effects of experiences of teaching preschool children with special needs upon inferences of essential causes of handicaps by using a written case. The case was concerning a child with social difficulties caused by cognitive deficit of perceiving situations. Forty-sixteachers and thirty-one undergraduates inferred the individual essential causes of social difficulties through seven presented items. Factor analysis revealed three factors，which were "difficulty of perceiving situation (Factor 1)" , "difficulties of controllability of emotion (Factor 2)" , and "the problems of relationships between a target and his classmates(Factor 3)" , then cluster analysis was used. The main findings were as follows: (1) Most of undergraduates estimatedindifferently on three factors. (2) Teachers were split into two totally contrastive groups. One estimated high possibility of the Factor 1 and low possibility of the Factor 2. The other evaluated themin the opposite ways. (3) Differences between these two contrastive groups were not found in experiences and inservice training. These results suggested that theindividua1 differences in the inferencesof causes of difficulties were not dependent on just the amount ofexperiences but on more complicatedfactors such as individual life history. Also difficulty ofabstracting cognitive psychological knowledge or models from daily individual teaching experiences was suggested. Finally,necessity of sharing mutual perspectives of each teacher concerning the essential causes of difficulties for the adapted individual teaching was discussed.