This article examines attitudes toward mainstream society among Caribbeans and South Asians in Britain. Conventional wisdom predicts that Caribbeans should be more likely than South Asians to have positive attitudes toward British society, in part because Caribbeans are more socially and culturally assimilated. In addition, much of the current debate around ethnic minority alienation in Britain focuses on the fact that recent terrorist activity has primarily been committed by Muslim South Asians. This article presents evidence that runs counter to these predictions, with data suggesting that South Asians are more likely than Caribbeans to have high levels of positive national identification, high levels of trust, and less pessimistic expectations for discrimination in Britain. To account for these dynamics, I develop an argument about the importance of ethnic minority migrants' expectations. I claim that cultural and social assimilation increases expectations for incorporation. When migrants with high expectations face incorporation difficulties, they will be more likely to develop pessimistic attitudes. In comparison, cultural and social segregation lowers expectations for incorporation prospects. When migrants with lower expectations face incorporation difficulties, they will be less likely to have pessimistic attitudes. I use this argument to explain why Caribbeans are less likely than South Asians to have positive attitudes toward mainstream British society.