In this theoretical piece, I explicate the concept of bounded social media places (BSMPs), places within social media characterized by control over visibility such as private groups, servers, and chats. I distinguish these from public social media places (PSMPs), like algorithmically controlled content feeds and public groups, profiles, and pages. In doing so, I argue that political communication scholars engaged in multi-platform research can adopt an affordances perspective and use the affordance of visibility as an organizing principle to understand the broader social media ecology. Thus, they can differentiate between lower visibility BSMPs and higher visibility PSMPs across multiple platforms. This helps to address the limitations associated with using platform as a discrete object of study in multi-platform research. In particular, individual platforms are heterogenous and contain both lower and higher visibility places, which can be associated with distinct political outcomes. Furthermore, I identify four types of BSMPs and review political communication research on them, highlighting how the concept of BSMPs can help researchers tackle some of the limitations associated with this work as well as encourage scholars to conduct more multi-platform political communication research on these different BSMPs. I also outline specific ways in which the concept of BSMPs can facilitate more nuanced multi-platform political communication research and theorizing. Scholars can draw on this concept to more clearly identify their object of study, engage in more platform-agnostic and durable research, and present a more complete picture of multi-platform media ecologies and political communication.