This article argues that quantitative secularization research has made important progress in the last 20 years in seven areas. We have gained knowledge of how religion and religiosity are connected to insecurity, education, socialization, secular transition, secular competition, pluralism, and regulation. This has led to a better understanding of the causes and the form of the secularization process. In this article, the author discusses the new ideas that have led to these advances, the evidence that supports the claims, and the new problems that have appeared due to the progress made.