The importance of knowledge resources leads companies to adopt organizational forms likely to foster learning and knowledge sharing processes. However, for such processes to occur, employees should be motivated to initiate and feed them. Despite several studies focus on new organizational forms and many others on motivational issues for investigating organizational behaviors, a comprehensive view simultaneously exploring both organizational structure and the joint effect of intrinsic and extrinsic motivation (i.e. crowding effect) on knowledge sharing behaviour is missing. Based on this, we posit that extrinsic motivation moderates the relationship between intrinsic motivation and knowledge sharing, as well as between integrative mechanisms and knowledge sharing. We test our hypotheses on survey data collected from 754 workers of 23 international manufacturing firms. Our findings support our argument, suggesting practitioners to be aware of the complexity involved in designing flexible structures and providing rewards. The paper concludes by highlighting directions for future research