This study uses a qualitative methodology to explore mental health literacy, specifically perceptions of prognosis, which is typically investigated with a quantitative, questionnaire-based approach. Two vignettes--one of a person with schizophrenia and one with depression--were shown to three mental health nurses and three psychiatrists. During semi-structured, open-ended interviews, they were asked to discuss their thoughts about the prognosis for the patient presented in each vignette. Participants tended to use the terms 'prognosis' and 'outcome' interchangeably. Psychiatrists tended to be more guarded in determining a prognosis than nurses. Both groups emphasized the importance of clinical experience in formulating views. However, nurses also discussed the role of the multidisciplinary team, whilst psychiatrists emphasized their reliance upon the scientific literature in shaping opinions. Participants identified information relevant for incorporating into future vignettes, to allow more informed research into literacy. The results of quantitative mental health literacy research should be interpreted with caution. Simplifying responses to allow comparative analysis is necessary, but masks more complex and important interpretations. Further qualitative research is recommended, the results of which can inform more comprehensive quantitative studies in the area.