Caring for a young person experiencing first-episode psychosis is challenging and can affect carers well-being adversely. While some face-to-face approaches have achieved promising outcomes, they are costly and resource-intensive to provide, restricting their reach and penetration. Guided self-help in book-form (or bibliotherapy) is an alternative but untested approach in these circumstances. In this study, we aimed to evaluate carers beliefs about the usefulness of problem-solving guided self-help manual for primary carers of young people with first-episode psychosis.Methods: A qualitative process evaluation nested in a randomised controlled trial, conducted across two early intervention psychosis services in Melbourne, Australia. 124 carers were randomised to problem-solving guided self-help intervention or treatment as usual. We also undertook a qualitative process evaluation, using individual interviews, with a random sample of 24 of the intervention group. A thematic analysis of the qualitative data was undertaken, which is the subject of this paper. Interviews were conducted between January 2009 and September 2010.Results: Three themes were abstracted from the data, reflecting carers beliefs about the usefulness of the manual: promoting carers well-being, increasing carers understanding of and support for the young person with first-episode psychosis, and accessibility and delivery modes of the programme.Conclusion: This process evaluation highlights that guided self-help is useful in informing and supporting carers of affected young people. While there is scope for broadening the delivery modes, the approach is easy to use and accessible, and can be used as a cost-effective adjunct to standard support provided to carers, by community mental health nurses and other clinicians.