Objective Prominent models of cognitive behavior therapy (CBT) assert that case conceptualization is crucial for tailoring interventions to adequately address the needs of the individual client. We aimed to review the research on case conceptualization in CBT. Method We conducted a systematic search of PsychINFO, MEDLINE, Psychology and Behavioral Science Collection, and CINAHL databases to February 2016. Results A total of 24 studies that met inclusion criteria were identified. It was notable that studies (a) focused on the assessment function of case conceptualization, (b) employed diverse methodologies, and, overall, (c) there remains a paucity of studies examining the in‐session process of using case conceptualization or examining relations with outcome. Conclusion Results from the existing studies suggest that experienced therapists can reliably construct some elements of case conceptualizations, but importance for the efficacy of case conceptualization in CBT has yet to be demonstrated. Research that involves direct observation of therapist competence in case conceptualization as a predictor of CBT outcomes is recommended as a focus for future hypothesis testing.