Online randomised controlled trial to evaluate the clinical and cost-effectiveness of a web-based peer-supported self-management intervention for relatives of people with psychosis or bipolar disorder: Relatives’ Education And Coping Toolkit (REACT). We intend to make available individual participant data that underlie the results reported in this article, after de-identification. Data will be made available on request 12 months following article publication, and only to researchers who provide a methodologically sound proposal and where the proposed use of the data has been approved by an independent ethics review committee (“learned intermediary”) identified for this purpose. Proposals should be directed to rdm@lancaster.ac.uk.