In this dissertation, I explore the factors that influence local government responsiveness to minority needs in Britain. In particular, I investigate whether the presence of Muslim representatives in city councils improves substantive representation of Muslim interests across thirty-two London boroughs. Based on the existing literature on minority representation, I propose the contingency theory of descriptive representation. The contingency theory of descriptive representation posits that descriptive representation is a necessary yet not a sufficient condition for substantive representation of minority interests. I theorize that descriptive representation of minorities leads to improved government responsiveness to minority interests contingent on the percentage of minority representatives, the level of their party fragmentation and political incorporation, and the electoral competitiveness of the district. I use multivariate regression analysis to test the effects of these four explanatory variables. Furthermore, I evaluate the specific process of their interaction through case-study analyses of the London Boroughs of Tower Hamlets, Newham, and Hackney, while also investigating the role of representational styles of Muslim councilors on their political effectiveness. Overall, the results confirm the contingency theory of descriptive representation and conclude that substantive representation of minority interests is higher in districts with higher percentages of minority representatives who are politically incorporated and less fragmented along party lines. The findings also suggest that the proportion of ethnic minorities in the district has a positive impact, whereas electoral competition of the district does not have a significant effect on government responsiveness.