This paper examines the political behaviour and electoral integration of first-generation immigrants in Spain, focusing on their patterns of political participation, ideological positioning, and vote choice. Drawing on merged data from CIS Barometers, the analysis assesses the explanatory power of five major approaches in the literature on immigrant political behaviour: class-based voting, identity and pro-immigration preferences, perceived discrimination and ethnic hierarchies, political socialization in countries of origin, and the role of party supply in the host country.

The findings show that first-generation immigrants display lower levels of electoral participation than native citizens, alongside a consistent tendency to support left-wing parties. Notably, this leftward electoral bias persists even among individuals who place themselves towards the right on the ideological scale. Important differences across origin groups are also identified: immigrants from Western Europe and Latin America tend to exhibit higher levels of political integration, while those from North Africa and Eastern Europe show larger gaps in both participation and political attitudes.

The results underline the importance of institutional factors—particularly unequal access to citizenship rights—as well as sociocultural and political-contextual variables in shaping patterns of political incorporation. Beyond the study of migration, the paper contributes to broader debates on electoral behaviour, representation, and political inequality in contemporary Spain.