The first chapter of this thesis is a systematic literature review exploring the relationship between help-seeking behaviour and psychosis (subclinical and clinical populations). An online search of databases was conducted and 19 studies met the inclusion criteria. The results of the literature search were extracted and synthesised to create a narrative review. The results provide some understanding of when, why and from whom people seek or do not seek help. Higher level of education, experiencing more than one psychotic symptom, and female gender increased likelihood of help-seeking. There were differences between self- and informant-reported reasons for poor help-seeking/service engagement. There were also differences in preferred sources of help across cultures. The analysed studies had limitations, and most were assessed as low in quality, which suggests that more robust designs and reliable measures need to be used to assess help-seeking in psychotic populations. The second chapter reports an experimental study exploring the impact of attachment priming (secure and avoidant) on state paranoia, help-seeking, and help-acceptance intentions in a clinical population. The self-selected sample (n=61) was recruited through an online research platform. Participants were randomly allocated to a secure or avoidant attachment priming condition and completed measures of state paranoia, help-seeking, and help-acceptance before and after the attachment manipulation. The findings showed that the secure attachment priming resulted in reduced paranoia and increased help-seeking and help-acceptance intentions, all with large effect sizes. This indicates causal links between attachment style and factors likely to affect duration of untreated psychosis. Additionally, this method could be used to facilitate service engagement with a group who face significant barriers to accessing recommended treatment.