In light of the growing criticism of multicultural policies of integration, there has been an increased interest in the questions surrounding political integration of immigrant-origin minorities. In particular, public and policy debates have focused on the importance of a shared sense of Britishness, the incompatibility of certain cultural values and practices, as well as the role of grievances and discrimination in determining the successful integration of the growing population of ethnic minorities. The work presented in this thesis consists of three separate studies that look at different aspects of political integration. The first study examines determinants of the strength of attachment to Britain among immigrant-origin individuals. Specifically, it looks at the role of: (1) indicators of integration and assimilation, (2) immigrants' conservative ideological beliefs, (3) the 'desirable' characteristics of immigrants, and (4) immigrants' placement on the individualism-collectivism scale. Empirical analyses are conducted using three datasets: Understanding Society, Citizenship Survey and Ethnic Minority British Election Study. The findings from individual and multi-level regression models show that collectivist orientation, determined by both individual differences as well as cultural differences of immigrants' countries of origin, is an important predictor of self-reported strength of British identity. In consequence, it is argued that the subjective importance of Britishness among immigrants is perhaps associated with integration/assimilation outcomes to a lesser extent than it is commonly believed. The second study presented in the thesis examines the applicability of the arguments derived from group consciousness and assimilation theories for explaining the patterns of political participation among British ethnic minorities. The chosen indicators of assimilation and group consciousness include: (1) measures of attachment to national and ethnic community, (2) perceptions of ethnic grievances, and (3) embeddedness in national versus ethnic civic community. The statistical analysis based on EMBES data shows that group consciousness indicators have a mobilising effect on non-electoral activities, and influence political party as well as ethnic-specific policy preferences. On the other hand, greater embeddedness in the national rather than ethnic community has a positive effect on electoral participation. Therefore, it is argued that both theoretical approaches are relevant for understanding political involvement. However, the effects of group consciousness and assimilation indicators operate in more nuanced ways than the classical formulations of these theories would predict. The final study examines the role of ethnic organisations for political mobilisation of two distinct communities: Bangladeshis and Caribbeans based on the data from forty qualitative interviews with community activists located in Birmingham and Oldham. The comparative qualitative enquiry aimed to (a) explore whether the existing differences of political integration outcomes between the selected communities can be partially attributed to the character of their co-ethnic organisational networks; and (b) to explore how and why co-ethnic associations might affect the political mobilisation of local communities. The findings from the interview data indicate that activists from these two communities have very different attitudes towards political agency and the role of co-ethnic organisations. In general, most of Bangladeshi organisations can be described as having instrumental goals and pro-mainstream orientation, whereas most Caribbean organisations could be characterised as having expressive goals and anti-mainstream orientation. In consequence, it is argued that the different character of ethnic civic organisations has an important impact on the ways these communities engage in politics, both as individuals and as groups.