Many people with psychosis do not engage in psychological treatments when offered. We examined variables that predicted uptake of group cognitive behavioural therapy (CBT) in first-episode psychosis. We assessed all consenting consecutive referrals over a 2-year period. T-tests and logistic regressions examined factors which predicted uptake. The suitability for short-term CBT scale (SSCT) and negative symptoms successfully differentiated engagement and non-engagement. A model combining negative symptoms and the SSCT significantly predicted uptake of group CBT. Attention has not been paid to poor uptake of psychological treatments in psychosis. This may have a greater impact on outcomes than treatment effectiveness.