The efficacy of problem solving therapy in reducing mental and physical health problems: A meta-analysis John M. Malouff ⁎ , Einar B. Thorsteinsson, Nicola S. Schutte School of Psychology, University of New England, Armidale, NSW, 2351, Australia Received 13 July 2005; accepted 17 July 2005 Abstract This paper describes a meta-analysis of 31 studies that examined the efficacy of problem solving therapy (PST). The meta- analysis, encompassing 2895 participants, showed that PST is significantly more effective than no treatment (d = 1.37), treatment as usual (d = 0.54), and attention placebo (d = 0.54), but not significantly more effective than other bona fide treatments offered as part of a study (d = 0.22). Significant moderators included whether the PST included problem-orientation training, whether homework was assigned, and whether a developer of PST helped conduct the study. © 2006 Elsevier Ltd. All rights reserved. Keywords: Problem solving; Therapy; Treatment; Efficacy; Meta-analysis Problem solving therapy (PST) developed out of a trend toward providing psychotherapy by teaching clients psychosocial skills (D'Zurilla & Goldfried, 1971). PST involves teaching a client how to use a step-by-step process to solve life problems. The usual process taught can be broken into two major parts: (a) applying a problem-solving orientation to life and (b) using rational problem-solving skills. Applying a problem-solving orientation usually involves appraising problems as challenges, thinking that the problems can be solved, and realizing that effective problem solving tends to require time and systematic effort (Nezu, 2004). Rational problem-solving skills include: (1) attempting to identify a problem when it occurs, (2) defining a problem, (3) attempting to understand the problem, (4) setting goals related to the problem, (5) generating alternative solutions, (6) evaluating and choosing the best alternatives, (7) implementing the chosen alternatives, and (8) evaluating the efficacy of the effort at problem solving (D'Zurilla & Nezu, 1999). If the efforts to solve the problem fail, one may return to any step and try again. PST typically involves oral and written presentation of the steps by the therapist, along with guided practice, both in session and as home assignments, in solving real problems. Developers of PST recommend that clients receive 8–16 sessions of 1.5 to 2 hr each (D'Zurilla & Nezu, 1999). Over the past few decades dozens of articles have been published reporting evaluations of the efficacy of PST with a wide variety of problems, such as deliberate self-harm, depression, and obesity. D'Zurilla and Nezu (1999) summarized results of many of the older articles, including studies that included PST mixed in with other treatment components such as Clinical Psychology Review 27 (2007) 46 – 57 ⁎ Corresponding author. Tel.: +61 2 6773 3776. E-mail address: jmalouff@une.edu.au (J.M. Malouff). 0272-7358/$ - see front matter © 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.cpr.2005.12.005