This chapter illustrates how citizens can enact varying styles and degrees of political engagement through social media. It also investigates if citizens engage with political content in ways unhindered by national boundaries. We distinguish between three primary types of content styles (factual, partisan, and moral) and four degrees of engagement (making, commenting, diffusing, and listening). Moreover, we argue that differences in Twitter and Facebook’s “digital architectures” encourage certain styles and degrees of engagement over others, and that the two social platforms sustain different levels of transnational activity. Supporting our argument with European cases, we suggest that Twitter is more suitable to fulfill social media’s transnational promise than Facebook, which is better adept at stimulating political participation.