The success of open source software like Apache or Linux not only attracts practitioners of IS to look more thoroughly on the development processes of these communities but also attracts researchers to take a closer look on how these communities work. At first glance open source software development is seemingly chaotic and anarchistic (Kuwabara, 2000). However, successful open source software communities like Apache or Linux do have strong leadership, management, and governance structures (apache.org, 2003; Bretthauer, 2002; Fielding, 1999). In these communities single individuals or a group of participants exercise leadership functions and are in charge of the project direction and survival. Currently, a strong focus of the open source software (OSS) literature is especially on the motivation of participants who spend a lot of time and effort without getting a direct monetary compensation. So far, only little is known about how these communities are organized, managed, and governed. This paper will concentrate on successful practices of effective leadership in OSS communities as an example of virtual communities. Specifically, we will look how leadership behaviors influence project performance. A conceptual model of how leadership behaviors influences project performance considering several contingencies will be developed, presented and propositions as well as testable hypotheses will be derived.