This paper measures parents' beliefs about school and peer quality, how information about each affects school choices, and how social interactions mediate these effects. Parents underestimate school quality and overestimate peer quality. Cross-randomized school and peer quality information combined with a spillover design shows that when parents received information, they and their neighbors' preferences shifted toward higher value-added schools, underscoring stronger tastes for school quality and the role of social interactions. Increased enrollment in effective schools improved socio-emotional outcomes. The experimental evidence shows parents value school effectiveness even conditional on peer quality and that social interactions strongly influence school choice.