This exploratory analysis of student attendance at science museums finds that student achievement in science and mathematics is somewhat higher for those students who visited science museums frequently during the school year or summer. The strength of the association with cognitive achievement is sufficiently noteworthy to encourage further analysis of the role of informal activities such as museum attendance on cognitive learning. The association of cognitive performance with science museum visiting was found to be only partially a product of student selectivity of parents with higher educational levels or prior achievement at earlier grades. However, student attitudes of science efficacy, utility, and anxiety in middle school were not found to be predictive or a result of frequent science museum attendance or achievement in later high school years, although attitudes and cognitive achievement did become more aligned by the 12th grade. But, no evidence is found in the analysis of the Longitudinal Study of American Youth (1987-1993) and the 2009 High School Longitudinal Survey that visiting science museums was associated with reversing the typical trend of decline in student reports of science self-efficacy or beliefs in the utility of science during high school years.