In this paper, we quantify the religious factor in private education in the United States by estimating a random utility model of school-choice in which households choose among public, private-nonsectarian, Catholic and Protestant schools. The model is estimated using a multinomial logit regression of attendance at different types of private schools using individual data from the General Social Survey. We find that both religion and religiosity have important effects on the demand for private schools. We also provide evidence that previous studies that do not take into account religiosity probably over-estimate the positive influence of private schools on measures of educational attainment. Evidence on the magnitude of this bias is presented.