Psychotherapy treatment manuals for adult populations (1950-2025): A scoping review.

Treatment manuals are essential for the development, evaluation, dissemination, and implementation of psychotherapeutic interventions. However, no comprehensive review has examined the existing landscape of treatment manuals for adult populations. This scoping review identified 1132 book-based treatment manuals published between 1957 and 2025 using traditional and API-based search methods across Google Books, WorldCat, and PsycINFO. A majority of manuals have been published since 2000 (n = 880; 77.7%), with over half published after 2010 (n = 592; 52.3%). Across manuals, 98 distinct clinical targets were identified. The most frequently targeted concerns included transdiagnostic substance use (12.0%), posttraumatic stress disorder (11.7%), major depressive disorder (10.5%), and transdiagnostic anxiety symptoms (9.8%). Theoretical approaches were most commonly integrative (33.0%) or second-wave cognitive behavior therapy (CBT; 25.6%), both spanning a range of clinical targets and demonstrating the greatest growth in publication over time. There was also a notable degree of overlap in clinical targets within specific theoretical orientations (e.g., 45 seconds-wave CBT manuals for major depressive disorder). Adapted treatment manuals were relatively uncommon (10.0%), most frequently addressing gender (n = 43) and rarely focusing on culture (n = 2), sexual orientation (n = 3), or race/ethnicity (n = 5). Only 13.3% of treatment manuals were recognized in evidence-based treatment guidelines. Overall, treatment manuals continue to increase in number, but their proliferation varies substantially across orientations, clinical targets, and populations. Future work is needed to improve the accessibility and effectiveness of treatment resources to better inform the dissemination and implementation of effective treatments.