This study deals with individual managerial performance, both overall and in generating innovation. While prior work has demonstrated a relationship between network structure and managerial performance, inadequate attention has been paid to network content. We consider several micro-social processes that might account for differences in managerial performance, taken from economic sociology and studies of managers' exploitation of their social networks and derived from work in psychology on the genesis of ideas. We compare the influence of these mechanisms on managerial performance using a sample of 106 middle managers in a European telecommunications company. Our findings suggest that, while network structure matters, access to heterogeneous knowledge is of equal importance for overall managerial performance and of greater importance for innovation performance. Copyright © 2004 John Wiley & Sons, Ltd.