In recent years there has been a renewed scientific interest in the study of religiosity, including research on genetic and environmental contributions to religiosity. In this article, we investigate genetic and environmental effects on 7 religiosity factors and explore how genetic and environmental effects covary across these factors. Seven religiosity factors estimated from 78 items were examined in a sample of adult male and female twins. The 7 religiosity factors were largely influenced by additive genetic and unique environmental effects, with relatively little influence from common environmental effects. Multivariate genetic analyses found the 7 religiosity factors were influenced by 1 common additive genetic factor, 3 common unique environmental factors, and unique environmental effects specific to each religiosity factor. The results suggest that for the population studied, additive genetic and unique environmental effects largely account for the variance across the religiosity construct.