During the years 1964 to 1971 a nationally representative sample of MZ and DZ twins and controls was followed through the Swedish compulsory school. The main purpose was to study physical and mental growth during puberty as well as heredity-environment influences on these growth processes. After 20 years a follow-up has been made of this sample with the purpose of investigating heredity-environment influences on life situation and self reported health at mid-life in relation to background factors collected during adolescence. 43 pairs of MZ twins, 90 pairs of DZ same sex and opposite sex twins as well 322 controls agreed to participate. A questionnaire was sent out to this group dealing with their present life situation such as family structure, economy, education and occupation. Other areas of interest were self reported health and ability to cope with their present life situation. The disadvantages found for MZ female twins at adolescence seem to persist at mid-life and ratings of school adjustment were related to coping ability as grown ups. This first report presents comparisons between twins and controls as well as males and females. To estimate heredity influences intraclass correlations for the twin pairs are calculated and for coping ability such influences seem to be quite conspicuous. Sex specific factors seem to operate regarding coping ability and satisfaction in educational choice and level. Generally, the results-indicate some advantages for the males regarding self reported life situation and health. Possible reasons for such sex differences are discussed. This study has been supported by grants from the Swedish Council for Social Research.