The present study describes age differences in the occurrence of career activities among profit sector and non-profit sector employees in the Netherlands. Three different types of variables have been studied, i.e. individual, job-related and organizational variables. Hypotheses have been tested with original survey data from 423 profit sector employees and 136 non-profit sector employees. The employees are all working in higher-level jobs in large organizations. Overall, we may conclude from this study that the differences between profit sector and non-profit sector workers are not consistent at all. For some factors the situation is more advantageous for profit sector employees, whereas for other factors the outcomes point in the opposite direction. Regarding age effects, we have found that, in general, for profit sector employees the differences between starters (20–34 years) and middle-aged workers (35–49 years) are not univocal, whereas the differences between middle-aged workers and seniors (over-fifties) imply that the amount of individual initiatives and organizational activities is less for the latter group of employees. When the three age groups are compared for the non-profit sector employees, most factors do not vary significantly. For the factors where the F-test is found to be significant, by and large, the situation regarding the possibilities for a further career development is worst for the seniors.