Cross-sectional studies of the factors explaining local government responses to immigrants fail to account for the fact that municipal responses often change over time even as many contextual characteristics remain constant. Drawing on 286 interviews across four new immigrant destinations, I examine local government responses to immigrants from 1990-2010. I find that external factors are particularly influential in shifting local responses over time, by redefining how residents understand immigrants. In keeping with other scholars, I find that external factors such as federal policies and the national political context interact with local characteristics to shift policy responses (Marrow 2009, Hopkins 2010). In addition, I identify a third factor–external scrutiny–that shapes the trajectory of local responses. When local governments respond restrictively toward immigrants, external scrutiny in the form of media and advocacy organization attention can define immigrants as protected minorities, rein in restriction, and, in some cases, encourage compensatory accommodation. Using an original database that compiles the current status of immigrant-related policies in 54 cities and towns that passed restrictive ordinances in 2006-2007, I test the hypothesis that external scrutiny is associated with reining in restriction. In a preliminary analysis, I find suggestive evidence of this association. In sum, I argue that heightened attention to external anti-discrimination policies and the economic costs of associations with bigotry define immigrants as protected minorities and motivate local officials to temper restrictive policies. On the other hand, when nationally salient immigration rhetoric defines immigrants as “illegal aliens,” this construction can override anti-discriminatory norms and open the door to restrictive responses.