Nuns and the effects of catholic schools. Evidence from Vatican II

This paper examines the causal effects of Catholic school attendance on educational attainment. Using a novel instrumental-variable approach that exploits an exogenous shock to the US Catholic school system, we show that the positive correlation between Catholic school attendance and student outcomes is explained by selection bias. Spearheaded by the universal call to holiness, the reforms that occurred at the Second Vatican Council produced a dramatic exogenous change in the cost/benefit ratio of religious life in the Catholic Church. Using the abrupt decline in the number of Catholic sisters as an instrument for Catholic school attendance, we find no evidence of positive effects on student outcomes.