ABSTRACT. From a cohort of 971 Swedish children followed up from birth through 15 years of age, all the children who had shown an increment in relative weight of more than 15 % (measured weight in % of standard weight for height) between the ages of 7 and 10 years (group A, n= 25), 10 and 13 years (group B, n= 23), and 7 and 13 years (group C, n= 22) were selected for the present study. For each case a control matched for sex and relative weight at 7 (groups A and C) or 10 years (group B) was selected. The degree of psychosocial stress was estimated by two raters on the basis of all the accumulated data in the school health records and of the personal knowledge of the school nurses. There was good agreement between the raters. A significant difference in the degree of psychosocial stress was found between cases and controls. An analysis of specific items revealed differences with respect not only to soft data, but also to objective facts (continuation of school after completion of the nine years of compulsory school). It is concluded that a rapid weight gain during school years may be an indicator of psychosocial problems.