His primary area of teaching and research is sociology of religion, with a specialization in the academic study of new religious movements.
[3] Bromley has written about the rise of an anti-cult movement in the 1970s and 1980s, and the accompanying controversies involving allegations of brainwashing and deprogramming.
In its dealings with the larger society, Bromley argues, religious groups can be either allegiant, contestant, or subversive of mainline values and institutions.
Groups perceived by the society as "subversive" have "apostates", who claim that the movements they have left are dangerous or criminal, and are taken seriously by mainline institutions and media.
Bromley compared these social conflicts to witch-hunts of the late Middle Ages, and has claimed that civil liberties guaranteeing religious freedom were threatened.
He has criticized the tactics of anti-cultists and their claims over brainwashing in several books and articles coauthored with Anson Shupe, such as Strange Gods, Moonies in America, and The New Vigilantes.