Using longitudinal data of IT professionals’ activities in the SAP Community Network, and the career histories of these professionals obtained from LinkedIn, we investigate the relationship between an individual’s participation in Internet-enabled open knowledge communities and a major event of his/her career development: job-hopping. We measure individual participation in open knowledge communities by two dimensions of related activities: contribution and learning. We provide empirical evidence that contribution to knowledge communities leads to a higher likelihood of job-hopping, yet a greater amount of learning is associated with a higher probability of retention. We argue that the effect of contribution can be attributed to job market signaling and the effect of learning is primarily driven by enhanced job performance and career advancement within the current organization. A series of robustness tests were conducted to address the self-selection bias and to rule out some possible alternative explanations to these mechanisms. Our work contributes to the existing body of literature on networks of practice and provides supporting evidence that participation in these networks indeed leads to career benefits and status advancements. Additionally, our study takes the first step to fill the gap in the current literature on voluntary employee turnover that has so far ignored the impacts of employee participation in external knowledge communities, thus providing both theoretical and practical insights in the area of organizational research.