Yapko attended the University of Michigan in Ann Arbor, where he earned a B.A. in Psychology in 1976, before attending United States International University in San Diego for graduate studies, earning an M.A. in Psychology in 1978, and his Ph.D. in Professional Psychology, Clinical Specialization in 1980. He is licensed in California as both a psychologist and marriage and family therapist. He opened a private practice in 1979, which he maintained until retiring from clinical practice in 2007 to focus on writing and teaching. He now regularly conducts clinical trainings in the areas of treating depression, psychotherapy, and applying clinical hypnosis. In addition to his private practice, he served as the director of The Milton H. Erickson Institute of San Diego. A non-profit organization for the study of psychotherapy, it is focused on training health and mental health professionals through conferences and workshops. He was also a founding member of the editorial board for The Ericksonian Monographs, a journal on Ericksonian hypnosis and psychotherapy.
During the 1980s, Yapko was a member of the faculty at the National University, San Diego, as well as a faculty member at United States International University, San Diego. From 2001 to 2004, he wrote the "Managing Your Mood" column for Psychology Today. He is currently a member of the board of advisory editors for the American Journal of Clinical Hypnosis. He also serves as an editorial consultant for the International Journal of Clinical and Experimental Hypnosis.
A proponent of Ericksonian techniques, Yapko employs hypnosis and other non-drug-based therapies in the treatment of depression. In his books and articles, he presents the view that the depression is a multidimensional disorder with multiple causal factors, including biological, psychological and social influences. As a result, he feels that patients respond better to psychotherapy in many cases, and that while the use of antidepressants may be called for in some cases, they are often overutilized with too little being known about their efficiency or long-term effects.
In the 1990s, Yapko generated some controversy among mental health professionals for saying that many therapists use inappropriately suggestive techniques to help patients recall repressed memories of childhood sexual abuse, memories that are sometimes suggested by the therapists themselves. In a survey he conducted of nearly 1,000 professional therapists, he reported that almost 19 percent of those surveyed said they knew of cases where they believed that a patient's trauma had been suggested by their psychotherapist, rather than based on a genuine experience. His 1994 book Suggestions of Abuse: True and False Memories of Childhood Sexual Trauma addressed the issue, suggesting that some therapists use inappropriate techniques, including checklists of symptoms such as depression, low self-esteem, headaches, obesity, arthritis and acne, to diagnose sexual abuse that never actually occurred. One critic, Lenore Terr, a San Francisco psychiatrist and author of Unchained Memories, stated in an interview that she felt that Yapko "overstates the problem" but she admitted that "it sometimes happens".
Two legal scholars noted that Yapko was careful to distinguish between (1) cases in which someone knows all along that he or she was abused, (2) cases in which someone independently remembers repressed memories, (3) cases in which a therapist facilitates recall of genuinely repressed memories, and (4) cases in which a therapist suggests memories of abuse; the scholars noted: "Unfortunately, many who share Yapko's concern about improper suggestion fail to heed his caution about reserving judgment until cases are examined on their facts."
Yapko is a member of the American Psychological Association, and a clinical member of the American Association for Marriage and Family Therapy. He is also a member of the International Society of Hypnosis, and a fellow of the American Society of Clinical Hypnosis. He is a three-time winner of the Arthur Shapiro Award for the best book of the year on hypnosis from the Society for Clinical and Experimental Hypnosis, winning it first in 2001 for Treating Depression with Hypnosis, then in 2006 for Hypnosis and Treating Depression, and again in 2012 for Mindfulness and Hypnosis. He is also a recipient of The Milton H. Erickson Award of Scientific Excellence for Writing in Hypnosis from the American Journal of Clinical Hypnosis. In addition, he has been the recipient of the American Psychological Association's Division 30 Award for Distinguished Contributions to Professional Hypnosis, the Pierre Janet Award for Clinical Excellence from The International Society of Hypnosis (a lifetime achievement award), and The Milton H. Erickson Foundation's Lifetime Achievement Award For Outstanding Contributions to the Field of Psychotherapy.