In this paper we provide the first rigorous evidence of the impact of a partnership between public middle schools and informal science institutions (ISIs), such as museums and zoos, on student outcomes. This study focuses on Urban Advantage (UA), a program in New York City (NYC) that explicitly draws upon the expertise and resources of the city's ISIs, bringing these institutions together with NYC public schools to improve science education through intensive professional development, access to ISIs for teachers and students, and other science resources. We conclude that attending a UA school in eighth grade increases middle school science achievement, and there is some evidence that it may also increase the likelihood of passing standardized science exams in high school. [Major public support for Urban Advantage is provided by the Speaker and the City Council of New York and the New York City Department of Education.]