This study tested the influence of bridging and bonding social capital in political participation while controlling for sociodemographic and psychological factors among Mexicans and Mexican Americans in Illinois. Bridging social capital significantly predicted two types of participation. Participants who felt their lives were linked to those of Anglo-Americans and attended functions with members of this group were more likely to contact a public official. In addition, those who attended functions with Anglo-Americans were also more likely to work for or contribute to a political candidate. Bonding social capital significantly predicted attending a public meeting or demonstration. Those who felt more linked to other Latinos in the country were less likely to participate, but those who had a close experience with discrimination were more likely to do so. Overall, findings showed that an understanding of the different aspects of social capital is necessary to decipher the participation puzzle. (Contains 1 table and 1 note.)