Social determinants over the life course, including childhood family characteristics, were studied in predicting unsuccessful entrance into the labour market at the age of 31 years. Among men, unsuccessful entrance into the labour market was predicted prospectively by the mother's receptive attitude towards receiving social aid and contentment with existing circumstances in early childhood, the family's low social status in adolescence, and low vocational education in early adulthood. Among women, it was predicted prospectively by low school attainment in adolescence and low vocational education in early adulthood, and associated cross-sectionally with having more than two children. Among both genders having a low income, poor subjective health and poor life satisfaction, as well as receiving little social support associated with unsuccessful entrance into the labour market. The results emphasize the role of childhood social factors in preventing long-term unemployment in young adulthood.