Psychotherapy continually evolves through innovative approaches, with single-case methodology gaining prominence for its detailed insights into individual psychological interventions. This article briefly explores the historical roots and empirical foundation of the single-case methodology and underlines the significance of single-case methodology in psychotherapy by stressing the limitations of group studies and advantages of single-case studies. It then exposes some of the most frequent designs with their pros and cons, presents a scale to assess methodological biases relevant for appraising the scientific literature on single-case studies and for planning research in the field, exposes guidelines to publish single-case research articles as well as briefly introduces relevant elements related to data analyses and statistics. The resurgence of single-case methodology in the 21st century, driven by advancements in statistical methods and influences from evidence-based medicine and education, underscores their growing importance. The flexibility of this methodology allows for adaptation to various research and clinical settings, accommodating complex and individualized treatment plans.

This article aims to guide clinicians and researchers in the field of cognitive and behavior therapy in conducting and publishing single-case studies with a rigorous methodological approach, highlighting the value of single-case methodology in advancing personalized, evidence-based psychotherapy.