Online Communities (OCs) have become an important source for identifying the needs and problems of users, supporting companies to innovate. This development was fostered by IT/Internet technologies and has also been strengthened through recent social changes in user behavior within the "Web 2.0". In contrast to its growing relevance, virtual user innovation activities still are underexplored. Companies that wish to successfully utilize and integrate innovative OC members into their NPD process need a better understanding of the drive and changes of user motivation in such Innovation Communities. We would like to contribute to filling this gap. In this paper we analyze, categorize and integrate different motivational factors that play a major role here and develop several propositions concerning motivation within Innovation Communities.