ISRCTN42478021.

Trial name or title	Combined individual and family cognitive behavioural therapy compared with treatment as usual
Methods	Allocation: randomised (using secure telephone, 1:1 ratio) Blinding: double Setting: UK Inclusion criteria: aged 16‐35 years, screen positive on CAARMS for at‐risk mental state, living with at least one member of their family, help seeking Exclusion criteria: receipt of antipsychotic drugs, moderate‐severe learning disability, organic impairment, insufficient fluency in English Duration: 12 months
Participants	Diagnosis: UHR for psychosis N = 76 Age: 16‐35 years Sex: men and women
Interventions	1. Individual + family therapy: maximum 25 individual therapy sessions, ˜1/week, 1 h, over 6 months, (focusing on whatever most concerned participant) + 4‐6 sessions of CBT with key family members or family support members (focusing on making sense of experiences, communication styles, problem solving and goal setting) + TAU, routine care from their care team or GP 2. TAU
Outcomes	Mental state: transition to psychosis (CAARMS defined), BDI, SIAS Health and social care: adapted EPQ, EQ‐5D
Starting date	March 2016
Contact information	Greater Manchester West Mental Health NHS Foundation Trust Psychosis Research Unit, Rico House, Harrop House, Bury New Road
Notes	Protocol registration: ISRCTN42478021