Old (60-70 years) and young (18-25 years) adults performed two experiments in which they had to learn to operate a simulated device. It was assessed whether age differences in performance were comparable over groups with different levels of foreknowledge. Of particular interest was the question how age differences between groups with limited foreknowledge compared to those between groups with foreknowledge. The role of complexity of operating procedures was studied by using tasks which differed in the number of actions that was needed for completion. In experiment 1, which employed three complexity levels, no effects of age were found as a function of presence of foreknowledge or complexity of procedures. Experiment 2, however, which employed an additional complexity level, showed that the performance of old adults with foreknowledge was poorer than that of young adults with foreknowledge. Complexity had no differential effect with respect to either age or amount of foreknowledge.