This study examines how socioeconomic inequalities in perceived health were reproduced as a cohort of adult men became 10 years older, and focuses especially on the role of social causation and health-selective mobility. A two-wave panel data set collected by the Nord-Trøndelag Health Study (HUNT), Norway, is used, and the study is based on a sample of 9189 men aged 25-49 at baseline. Systematic socioeconomic inequalities in perceived health were observed both at baseline and 10 years later when the sample was aged 35-59. Measured as age-adjusted percentage differences, inequalities in perceived health widened during the study period, both among those who were continuously employed and between the employed and non-employed. The pattern of health inequalities was transformed as a result of numerous changes in perceived health and considerable social mobility during the study period. Compared to higher white collar, changes in perceived health during the study period were more negative among medium-level and manual occupations, and even more negative among the non-employed. Mobility between occupational classes among those employed at both observation points was not selective for health, but transitions into and out of employment were strongly health-selective. It is argued that the transformation of the health inequality pattern among those continuously employed was solely due to social causation, i.e., to more negative changes in perceived health among medium/manual occupations than among the white collar. The wider difference in perceived health between the employed and non-employed was, however, primarily a result of health-selective mobility into and out of the non-employed category.