In response to COVID-19, U.S. students learned remotely from mid-March to June 2020. At the start of academic year 2020--21, many schools remained remote but others--primarily Catholic and other private schools--reopened. We consider Catholic schooling as a proxy for in-person instruction and use national data from Renaissance Star and MAP Growth assessments to compare the achievement of similar students pre-pandemic, during the height of mitigation strategies, and after most schools reopened. In a departure from pre-pandemic growth patterns, students in Catholic schools showed more growth than those in public schools during the height of mitigation strategies, suggesting the importance of in-person instruction.