Clients come to psychotherapy because they have difficult and stressful problems that they are unable to resolve on their own. Advances in the applied problem-solving literature can now inform clinical interventions. This article focuses on the most commonly used problem-solving assessment tool, the Problem-Solving Inventory (PSI); empirical findings from well over 120 studies are used to inform clinical practice. The article will first discuss the PSI, what it measures, and then summarize the empirical research findings most relevant for clinical interventions. Second, based on the PSI empirical research, therapeutic and preventative implications will be discussed with clinical illustrations. The article concludes with a number of implications for psychotherapy both in terms of remedial and preventative interventions.