Schwartz received his PhD from Harvard University, and was a professor of psychiatry and psychology at Yale University as well as Director of the Yale Psychophysiology Center and co-director of the Yale Behavioral Medicine Clinic from 1976-1988. He is the Director of The VERITAS Research Program of the Human Energy Systems Laboratory in the Department of Psychology at the University of Arizona.

In his early career Schwartz published extensively on biofeedback research, and health psychology. Schwartz's major research focus for the past ten years has been in the field of parapsychology. The goal stated by VERITAS is to test the hypothesis that the consciousness of a person survives physical death. To this end, Schwartz has performed experiments at the University of Arizona that tested well-known mediums such as John Edward of TV's Crossing Over and Allison DuBois, the inspiration for the TV drama Medium. Based on research that Schwartz has characterized as formal scientific experiments under controlled conditions as well as informal readings on himself, Schwartz concluded that DuBois could indeed contact dead people, saying, "There is no question this is not a fraud, some people really can do this, and Allison is one of them." Schwartz says his experiments with DuBois included a reading for celebrity physician and author Dr. Deepak Chopra following the death of his father that Chopra characterized as 77% accurate.

Schwartz's methods have prompted criticism by skeptics such as University of Oregon professor Ray Hyman, who says they deviate from the accepted norms of scientific methodology, and criticizes Schwartz for research errors such as inappropriate statistical tests and using subjects predisposed to believe in psychic abilities. Skeptic Robert Todd Carroll maintains that Schwartz's evaluation of mediums is subjective and a product of wishful thinking. When skeptic James Randi asked the University of Arizona to submit Schwartz's research data to an independent panel for evaluation as part of his $1 Million Challenge, Schwartz declined. Schwartz has also been accused by psychic Laurie Campbell and Allison DuBois of exploiting their publicity value.

Schwartz is the co-author of The Living Energy Universe, and is the author of Breakthrough Scientific Evidence of Life After Death and The Truth About Medium as well as authoring over 450 scientific papers and editing academic books.