The purpose of this study is to understand in a practical sense the etiologicalbackground of social withdrawal and to find some clues on how to present itsoccurrence. We hypothesized that a lack of group experience and/or the disturbance ofthe daily rhythm including the sleep'wakefulness cycle at an early age might beinfluential factors for social withdrawal.To examine this hypothesis,we designed a questionnaire containing items aboutthe clients' experiences in nursery schools and kindergarten,the clients' bedtimes,wake times, playing hours, helping at home and other activities during theirelementary and junior-high school years and at the point of this survey. Forty-onesocial withdrawals with an average age of 27,85 and 172 students were participating inthis survey.In case of those 41 social withdrawals,their mean age of showing for the first timesymptoms of social withdrawing is 19.25土4.72.About half of the clients are the oldestchild in their family. The ratio of persons with group experience in nursery school wassignificantly lower in the social withdrawal group (χ2(1)ニ9.400,pく.05). The ratio ofpersons with group experience in nursery school from an early age(below age 3) and inkindergarten also tends to be lower in the social withdrawal group,although notsignificantly.As to the sleep-wakefulness cycle,the social withdrawal group tends to go to bedearlier and to rise later than the participants of the control group when they were inthe middle grades of elementary school and the second grade of junior high school,although again not significantly. On the other hand,at the point of this survey thesocial withdrawal group gets up significantly later than the controls.The ratio of persons who had breakfast every day when they were attending juniorhigh-school was lower among the withdrawals than the controls. The socialwithdrawals were playing less and hardly helped at home when they were in themiddle grades of elementary school and the second grade of junior high-school.These results were discussed in relation with the findings of our previous studyand others.