Personality disorders that leave clinicians feeling frustrated, manipulated, or burned out represent some of the most challenging cases in mental health – but they don’t have to derail treatment or destroy therapeutic relationships. Gregory Lester has spent over 40 years developing practical, no-nonsense approaches to personality disorder treatment, becoming one of the most sought-after trainers in this specialty area and training more professionals in personality disorders than any other individual.
As a licensed clinical psychologist in Colorado and Texas with over 3,500 patients personally evaluated and treated, Dr. Lester brings unparalleled real-world experience to his training programs. His four bestselling clinical manuals on personality disorder diagnosis and treatment, combined with his widely-read book Power with People: A Manual of Interpersonal Effectiveness (now in its 20th printing), demonstrate his ability to translate complex psychological concepts into practical strategies that actually work in clinical settings. His global reach – having presented over 2,000 trainings to more than 250,000 professionals in 132 cities worldwide – reflects his reputation as the definitive expert on managing difficult personality presentations.
Dr. Lester’s expertise spans comprehensive personality disorder assessment, evidence-based treatment approaches, interpersonal effectiveness strategies, and what he calls “management techniques” for the most challenging cases. His approach cuts through theoretical complexity to focus on what clinicians need to know to work effectively with clients who are manipulative, hostile, or treatment-resistant. He specialises in helping practitioners maintain professional boundaries, avoid burnout, and achieve therapeutic progress with clients others might consider “untreatable.”
What sets his training apart is practical wisdom gained from decades of frontline experience. Lester doesn’t just teach diagnostic criteria – he shows clinicians how to recognise subtle personality disorder presentations, how to structure treatment to prevent manipulation, and how to maintain their own psychological safety while providing effective care. His contributions to the DSM-5 Personality Disorders Section revision reflect his influence on how these conditions are understood and treated.
For your practice, expect to gain specific techniques for managing difficult therapeutic relationships, tools for accurate personality disorder assessment, and frameworks for maintaining professional effectiveness with challenging clients. His approach particularly benefits clinicians who feel overwhelmed by personality-disordered clients or want to develop specialised expertise in this high-demand area.
Quick Win: Lester’s “interpersonal effectiveness hierarchy” teaches clinicians to quickly identify which personality disorder patterns they’re dealing with and respond with the appropriate level of structure and boundaries – often preventing therapeutic crises before they develop.
Qualifications
- Ph.D., Clinical Psychology
- Licensed Clinical Psychologist (Colorado and Texas)
- Over 40 years clinical experience
- Personally evaluated and treated over 3,500 patients
- Research participant, DSM-5 Personality Disorders Section Revision
Authored Books
- Diagnosis, Treatment, and Management of Personality Disorders (bestselling clinical manual)
- Power with People: A Manual of Interpersonal Effectiveness (2nd Edition, 20th Printing)
- Personality Disorders: Personality Disorders in Social Work, Mental Health, and Health Care (clinical manual)
- Shrunken Heads (memoir of graduate school training)
- Central Intelligence Bureau: The Shrink, the Chip, and the Spy (spy thriller novel)
Teaching & Roles
- Clinical Psychologist, Private Practice, Colorado & Texas, 1985–present (40+ years)
- Consulting Psychologist, Healthcare companies and social service agencies, current
- Special Consultant, United States Department of Justice, current
- Trainer & Speaker, Continuing Education Seminars, current
- Graduate Faculty Member, University of St. Thomas
Training & Speaking
- Over 2,000 trainings presented on personality disorders
- Trained over 250,000 professionals in 132 cities globally (US, Canada, Australia)
- Most in-demand trainer on personality disorders topic
- Regular conference speaker and workshop leader
Featured Publications
- The Journal of the American Medical Association
- The Western Journal of Medicine
- The Journal of Behavior Therapy
- The Journal of Marriage and Family Therapy
- The Yearbook of Family Practice
- The Transactional Analysis Journal
- Black Belt Magazine, Restaurant Hospitality, The Skeptical Inquirer
Ready to work confidently with personality disorders and difficult clients? Discover how Dr. Lester’s proven strategies can transform your most challenging cases from sources of burnout into opportunities for professional growth and clinical effectiveness.