In recent years, the size of the Latino immigrant population has swelled in communities throughout the United States. For decades, social scientists have studied how social context, particularly a minority group’s relative size, affects the sentiments of the dominant group. Using a random sample survey of five communities in suburban Chicago, the authors examine the impact of Latino population concentration on native-born white residents’ subjective perceptions of threat from Latino immigrants at two micro-level geographies: the immediate block and the surrounding blocks. After controlling for Latino population size in surrounding blocks, percentage Latino in the immediate block does not influence perceptions of threat from Latino immigrants. The effect of surrounding blocks’ population size is consistent with group threat theories for white residents: the larger the Latino population, the greater the perceived threat.