The present analysis investigates skill requirements in the workplace, measured directly by the task-composition of occupations. It shows that the task composition of occupations has shifted toward analytical and interactive activities and away from manual and cognitive routine activities in West Germany between 1979 and 1999. These withinoccupational task changes account for around 50 percent of the educational upgrading in recent decades. The analysis shows additionally that computer technology is complementary to workers in executing analytical and interactive activities, whereas it substitutes for workers in performing manual and cognitive routine tasks. This relationship exists within occupations, within occupation-education groups and within occupation-age groups.