Dr. Justin J. Lehmiller is a social psychologist and one of the country's leading experts on human sexuality. He is currently the Director of the Social Psychology Program at Ball State University and a Faculty Affiliate of The Kinsey Institute. Formerly, he served on the faculty at Harvard University.

In addition to being an award-winning educator, Dr. Lehmiller is a prolific scholar who conducts research on sexual fantasy, casual sex, secret relationships, and safer-sex practices. He has authored dozens of scientific publications and is the author of the sexuality textbook The Psychology of Human Sexuality. Dr. Lehmiller is on the editorial boards of several prominent academic journals in the fields of relationships and sexuality, including the Journal of Social and Personal Relationships and Psychology of Sexual Orientation and Gender Diversity, and he is an elected full member of the International Academy of Sex Research.

Dr. Lehmiller holds advanced degrees in psychology, including a Master of Science from Villanova University and a Ph.D. from Purdue University.