We examined the impact of social media on political, civic, and online participation, taking into account the discursive architecture and deliberative nature of each platform, which was hypothesized to enhance these forms of engagement. Initially, we assessed the deliberative aspects of the Facebook, Twitter, and YouTube platforms. Subsequently, we investigated whether these aspects predicted participation through a national survey involving 1 750 participants. Our findings reveal a general influence of the platforms on participation and specific effects for each platform within each type of participation. However, these effects do not align with their respective levels of deliberativeness.