This dissertation consists of two chapters studying design choices by knowledge production platforms. The first chapter studies the impact of opening a supportive community that provides a different environment on knowledge exchange and user engagement in the main platform. I find evidence that the introduction of a supportive community improved performance for the focal community because of greater community engagement. However, absent a coordinating mechanism between the two channels, only a few selected questions are cross-posted to the chatroom. I next study how these patterns change with the introduction of such a coordinating mechanism—a “feed” that pushes all questions from the Q&A forum to the chatroom. Introducing a feed leads to faster answers relative to questions that are treated only by chatrooms, particularly for questions by new users. However, some feeds were turned off quickly, suggesting that feeds can create congestion. Our results lead to implications for the design of increasingly popular supportive channels in online communities. These channels have the potential to benefit disadvantaged users, but only if they are complemented by additional coordination mechanisms such as feeds. In the second chapter, I study platform bifurcation, the process in which a subgroup of users from an original platform launches an independent spin-off platform. I identify the effects of bifurcation using a difference-in-differences approach that exploits the introduction of spin-off platforms in an online platform incubator. I find that bifurcation leads to a strong overall increase in contributions. While contributions to the home platform decline, the two bifurcated platforms generate more combined user contributions and attract more new users compared to a single united platform. I further explore how interconnectivity and platform differentiation affect users’ choice of platform. The evidence indicates that users are less likely to migrate from an incumbent platform to a new, specialized platform when interconnectivity is strong but more likely to migrate when the specialized platform enables more differentiation. This paper is the first to empirically analyze the strategic implications of new platform entry at scale and to document the moderating role of interconnectivity and platform differentiation.