This paper examines the effect of institutional contact on political participation among non-White communities. While both formal and informal institutions help shape community citizen participation, their effects vary on the historical inclusion (or exclusion) of certain racial groups. Formal institutions, like political parties, have historically excluded or neglected non-White and immigrant voters. We argue that for the excluded or neglected, non-traditional political institutions, like community based organizations, serve as supplements to facilitate political incorporation and engagement. These informal institutions help develop skills and resources among their constituents, and offer routine opportunities to participate. We use the 2008 Collaborative Multi-racial Post-Election Survey (CMPS) to test the differential effects of self-reported voter mobilization through nonpartisan and partisan institutional contact to explain variations among racial groups by the intensity of contact, occurrence of co-ethnic outreach, and type of institutional mobilization. We find that while contact by a partisan/political institution, like a political party or campaign, has an overall positive effect on political participation for all voters, contact by a nonpartisan/civic or community group is substantively more important for Latino and Asian American voter mobilization. Our analysis therefore offers cohesive evidence of how voters interact with and are affected by mobilization efforts that attends to differences across racial and ethnic boundaries, and variations in institutional contact.