This dissertation investigates an overarching research question: how can recognition-type incentives, such as gamification and peer gifting, motivate users' knowledge seeking and contributions in e-learning and online Q&A (question and answer) communities? To address this question, I conducted three studies. In Chapter 2, I examine how social comparison directions in a leaderboard affect people's learning performance and satisfaction in the e-learning community. I performed a randomized experiment with a control group as a comparison baseline. My findings reveal that learning effort, active discovery, self-efficacy, and self-expansion are essential mediators to understand the effects of social comparison directions. In Chapter 3, I examine how different designs of badge tracking affect users' knowledge contributions in a Q&A community. Drawing on reinforcement and goalsetting theories, I conceptualize two different badge tracking designs: backward tracking highlighting and forward tracking. To examine the differential effects of two designs, I first conducted a natural experiment with a different-in-differences analysis. My findings reveal that users earning forward tracking badges are more motivated to provide more knowledge contributions than those earning backward tracking badges. Further, according to each badge tracking design, I analyze the motivational patterns of users earning different levels of badges, high versus low. The results indicate that backward tracking promotes an increasing effect when earning badges of a higher level. However, forward tracking leads to a decreasing effect when earning badges of a higher level. In Chapter 4, I examine the impacts of peer gifting on knowledge contributions from the recipient's perspective in a Q&A community. Building on equity theory, I argue that receiving peer gifts can increase individuals' perceived levels of inequity, and therefore motivate their subsequent knowledge contributions positively. The results of a field experiment support my hypotheses, suggesting the positive effects of peer gifting in motivating recipients' knowledge contributions. Furthermore, I observe that increasing the monetary value of peer gifting can boost recipients' knowledge contributions; however, changing the recognition message in peer gifting from public to private can reduce recipients' subsequent knowledge contributions. Moreover, I find that these differential effects are likely to be moderated by gift recipients' reputations. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]