We exploit within-teacher variation in the years that math and reading teachers in grades 4–8 host an apprentice (“student teacher”) in Washington State to estimate the causal effect of these apprenticeships on student achievement, both during the apprenticeship and afterwards. While the average causal effect of hosting a student teacher on student performance in the year of the apprenticeship is indistinguishable from zero in both math and reading, hosting a student teacher is found to have modest positive impacts on student math and reading achievement in a teacher’s classroom in following years. These findings suggest that schools and districts can participate in the student teaching process without fear of short-term decreases in student test scores while potentially gaining modest long-term test score increases.