This study employs a qualitative meta-synthesis approach to analyze the relationship between internet-based social media and political participation in Iran. The research examines how social media influence political participation in Iran and how these influences vary across different political periods. Thirty-five scientific research articles meeting specific criteria were analyzed . Findings reveal that the relationship between social media and political participation in Iran is dualistic and context-dependent. Under conditions of relatively high political trust (periods 2009 and 2017), social media enhance formal participation (voting); however, under conditions of declining political trust (periods 2019 and 2022), social media primarily lead to increased unconventional participation (online protests). The findings also challenge the claim of "civil society expansion" and propose the concept of "transition from institution to network," wherein digital communicative action has expanded but remains in a state of "structural suspension"expanded yet unstable, active yet without institutional consolidation. This structural suspension stems from weak bridging social capital, declining political trust, class and geographical digital divides, and Iran's digital governance structure. The "network–power–trust interaction" model is presented as an analytical framework that integrates three layers: global (Castells' network society), intermediate (political economy of platforms and Habermas' public sphere), and indigenous (Iran's digital governance and Putnam's social capital). The model demonstrates that social media in Iran function not as automatic engines of democratization nor as mere instruments of political passivity, but as mediating variables within Iran's networked power structure, whose effects are entirely shaped by macro-structural variables