BACKGROUND: Guidelines on psychological and/or psychosocial assessment and intervention in the perinatal period can provide beneficial practice guidance for healthcare professions to reduce maternal distress and potential mortality. As little is known about the similarities in recommendations across guidelines, which could impact the quality of therapeutic intervention women receive, this systematic review was conducted to draw out the consistent guidance for perinatal psychological and/or psychosocial therapeutic input. METHOD: Eight literature and two guideline databases were searched alongside guideline development institutions, and organisations of maternity or perinatal mental health care. All relevant guidance was searched for and extracted before guideline quality was assessed using the AGREE-II instrument. Included guidelines had a primary or secondary focus on psychological assessment and therapeutic intervention for perinatal mental health difficulties. Using a narrative synthesis approach, recommendation consistencies and inconsistencies were outlined. RESULTS: From the 92 records screened, seven guidelines met the inclusion criteria. Only two guidelines were rated high (> 80%) across all assessed domains, with the other guidelines scoring between poor and excellent across domains. Highest rated domains across all seven guidelines were clarity of presentation (75%) and scope and purpose (70%). Recommendations for structured psychological assessment and intervention were most commonly reported in the guidelines; however, the level of detail and depth of information varied across guidelines. Whilst assessment and intervention recommendations for mother-infant dyad and partners were considered, research into working therapeutically with these client groups in perinatal mental health services is only just emerging. Hence, guideline recommendations for working with the mother-infant dyad and partners were based on consensus of expert opinion. CONCLUSION: Perinatal mental health guidelines were consistent in scope but showed considerable variability in quality and depth of recommendations, which could have implications for standards of clinical practice. However, there is still a need to improve the evidence underpinning recommendations in perinatal mental health guidelines to advance the implementation of psychological and/or psychosocial interventions. High quality interventions in the perinatal period could improve outcomes for women and their families.