--- - |2+ Objective This study estimates the effects of private schooling on noncognitive outcomes as measured by patterns of student responses on exams and surveys. Methods I use Programme for International Student Assessment (PISA) data from over 300,000 individual students within 44 countries in 2009 and a historical natural experiment to estimate the causal impact of private schooling on student effort. Since nations with larger shares of Catholics in 1900 tend to have larger shares of private schooling today, the study uses the Catholic share of the population in 1900 as an exogenous instrument to predict whether a given child is in a private school in 2009. Results The results suggest that private schooling increases student effort on PISA tests, as measured by test decline, while decreasing diligence on student surveys, as measured by careless answer patterns and nonresponse rates. In addition, I find that private schooling substantially increases PISA test scores, and that stronger noncognitive skills are associated with higher PISA scores. Conclusion Since this is the first study to connect school sector to these noncognitive outcomes, additional research on this topic is especially welcome. More research is also needed on the validity of measures such as test decline, careless answer patterns, and nonresponse rates. - 'Social Science Quarterly, Volume 100, Issue 6, Page 2256-2276, October 2019. '