Measurements and main results-The outcome variable was the attained educational level at age 24 to 30. Predictive variables described health related lifestyle and health at the age of 16 and 18. Those whose educational level was low at follow up, had in adolescence, a more health compromising lifestyle than those who had reached higher levels. They had placed less emphasis on health promoting behaviours like not smoking, physical exercise, good diet, and dental hygiene. Smoking was the outstanding predictor of attained educational level. Among the health variables, only psychosomatic symptoms predicted high educational levels in girls, and both psychosomatic symptoms and height in boys. Conclusion-Those who reach a high level of education in adulthood, have had a health enhancing lifestyle already in adolescence, while those reaching only a low level, have had a health compromising lifestyle. Health plays only a small part in the prediction of adult educational level. The results suggest that a health compromising lifestyle, adopted already in adolescence, is an important mechanism from which educational health diVerences originate. (J Epidemiol Community Health 1998;52:794-801)