OBJECTIVE Patient expectancies are known as a common factor contributing to psychotherapy outcome. Among expectancies, specific control expectancies (such as the perceived responsibility for change) can be considered of special clinical interest because of their connection with the engagement of patients in therapy. Attempts to study control beliefs in relation to psychotherapy outcome have been made by the locus of control research but received less attention in recent years. Based on findings from the expectancies literature (also including outcome and patient role expectancies), this systematic review proposes ways to reactivate the promising field of control expectancies in the psychotherapy context. METHODS The PsychInfo and PubMed databases were searched with the keywords 'expectancies', 'expectations', 'locus of control', and 'role expectancies'; these terms were cross-referenced with the terms 'patient', 'client', 'psychotherapy', 'treatment', and 'outcome'. A total of 35 studies published in the last 25 years and focusing on the relationship between patient expectancies and psychotherapy outcome were identified and included in this review. RESULTS The review of the literature shows a modest direct relationship between specific expectancies and clinical improvement. Studies focusing on the association between global expectancies and outcome led to rather inconsistent findings. CONCLUSIONS The study of control expectancies in psychotherapy has been neglected in the past years probably due to mixed results. The main reasons for inconsistency can be found in the scarcity of specific assessment measures for treatment expectancies as well as in the limited knowledge about process variables in the past. Implications for future control expectancies research are discussed, and a new rating scale is proposed as a possible tool for measuring control expectancies in the specific context of psychotherapy.