Study objectives: To assess the direct and indirect contributions of material, behavioural, and psychosocial factors to the explanation of educational inequalities in mortality simultaneously. Design: Prospective observational study (1991-1998). Setting: General population from south east Netherlands. Participants: 3979 men and women aged 15-74 years without severe chronic disease at baseline (1991). Main results: Material factors (type of health insurance, financial problems, and housing tenure), psychosocial factors (life events and external locus of control), and behavioural factors (smoking habits and physical activity) together reduced the relative risk of mortality of the lowest educated group from 2.57 (95% CI 1.43 to 4.64) to 1.01 (95% CI 0.50 to 2.03). Of these three groups of factors, material factors contributed most to the educational inequalities. Part of the contribution of materi