Objective: This study explored women's experience of puerperal psychosis (PP) and their perceptions of its cause, in order to contribute to an increased understanding of PP and promote consideration of new management perspectives. Background: Out of every 1000 live births, approximately one to two women will develop PP. The numbers are relatively small, yet the consequences can be devastating. Key theoretical explanations for the aetiology of PP are genetic, biochemical and endocrine. A small and relatively tenuous evidence base considers PP from a psychological perspective, despite acknowledgement of the need for broader understanding. A stress-vulnerability model has offered a contemporary explanation of psychotic symptoms in other contexts and non-clinical populations and may offer useful insight in relation to a psychobiological model of PP. Methods: In a qualitative study, seven women who had been diagnosed with PP previously were interviewed and the data subjected to an inductive thematic analysis. Trustworthiness and rigour of the study was assured by careful monitoring of the research process and data checking. Results: Four themes were identified - The path to PP; Unspeakable thoughts and unacceptable self; ‘Snap out of it'; and Perceived causes. While women attributed their PP to the physiological changes associated with childbirth, their accounts of PP began before and during pregnancy. Women highlighted stressful pregnancies characterised by significant challenges and emotions, difficult births and unsupportive family relationships postnatally. The experience of PP was extremely distressing. Conclusion: Findings add to the debate about a more multifaceted explanation of PP and potentially offer a psychobiological model of understanding.