Forensic psychiatry and forensic psychology face a common threat: the erosion of their credibility. It is proposed that they can combat this threat better by collaboration than by independent efforts. Similarities between the two professions are reviewed to examine their potential for collaboration. Their differences are reviewed to demonstrate the value of that which they can contribute collaboratively, beyond that which either can contribute independently, to increasing their credibility in the eyes of the public and the courts. Three specific areas for collaboration are proposed: individual practice, quality control of expert testimony, and training.