The role of the youth in societies is crucial for development, yet research has shown their declining engagement in formal forms of political participation such as voting. Through social media platforms, the youth can acquire social resources, such as political information, social services, or access to political officials and institutions, and as the most active online users, they can make use of these social resources to engage better in the society. However, the link between social media use and political participation needs further examination. Guided by the social network theory, this study examines the effects of social media use and the mediating effect of political communication networks on the political participation of the Filipino youth. Survey data was collected from 400 randomly selected respondents (15-24 years old) in Metro Manila and an ego network survey research design was implemented to identify and describe the youth's political communication networks. Structural equation modelling was used to test the theorised relationships among the variables. Results reveal the respondents' extensive use of social media and their low level of political participation. Meanwhile, the ego network analysis indicates that the youth do not engage in conversations related to political issues. Based on the statistical tests, the youth's political communication networks mediated the influence of social media use on their political participation. This implies that although the Filipino youth are in a good position to access and make use of social resources, their low political participation was partly due to their lack of communication with others. Courses of action and policies are recommended to maximise social media in engaging the youth in politics and promote the formation of political communication networks.