This paper studies leadership, conditions of influence and effectiveness in workplaces where a group form has been chosen. The study focuses on the interaction within work groups and between employees working in groups and their immediate superiors in a Swedish psychiatric hospital. Its aims are to investigate the effects of this interaction on degree of influence over work and on preconditions for working effectively. An attempt to achieve these aims is made by obtaining a more refined picture of the relation between superior and subordinate. The results show that there is a relationship between the support and opportunities for development that subordinates receive from their superior and the support that subordinates themselves give to their superior. Further, there are positive relationships between, on the one hand, the volume of exchange of social support and, on the other, personal work influence and preconditions for working effectively.