Meta-analysis in the American Journal of Psychiatry finds that, relative to other psychological interventions for psychosis, Cognitive Behavioral Therapy was significantly more efficacious at reducing positive symptoms of psychosis, and social skills training was more efficacious at reducing negative symptoms. The research, from Amsterdam and The Hague, compared data from 48 outcome trials consisting of 3,295 participants.
Turner, D., van Der Gaag, M., Karyotaki, E., Cuijpers, P.; Psychological Interventions for Psychosis: A Meta-Analysis of Comparative Outcome Studies. American Journal of Psychiatry. Online February 14, 2014 doi:10.1176/appi.ajp.2013.13081159