In this paper I consider the impact of attending a selective high school in the UK. Students are assigned to these schools on the basis of a test taken in primary school and, using data on these assignment test scores for a particular district, I exploit this rule to estimate the causal effects of selective schools on test scores, high school course taking and university enrollment. Despite the huge peer advantage enjoyed by selective school students, I show that four years of selective school attendance generates at best small effects on test scores. Selective schools do however have positive effects on course-taking and university enrollment, evidence suggesting they may have important longer run impacts.