Due to the rapid growth of social media, nearly 4 billion people now have online accounts where they engage with their social network, learn about the news, and share content with other people. The rapid growth of this technology has raised important questions about its potential impact on political action and polarization. We propose the SPIR Model to address how Selection, Platform Design, Incentives, and Real World Context might explain social media’s role in exacerbating polarization and intergroup conflict. Rather than simply asking whether social media as a whole causes polarization, we examine how each of these processes can spur polarization in certain contexts. We discuss how interventions might target each of these factors to mitigate polarization.