An Aggression Risk Profile was developed as an objective multidimensional scale for characterizing aggressive psychiatric patients and predicting verbal, physical, and general manifestations of aggression. Based on earlier studies, the 39-item Aggression Risk Profile incorporated demographic, diagnostic, historical, and clinical parameters. Its reliability, discriminative validity, and predictive validity were supported in its application to a total of 208 inpatients. Aggressive patients were more often found to be men, to be diagnosed with organic mental syndrome or substance abuse disorder, and to be notable in history of aggression. They tended to be angry and excitable but not more floridly ill than control subjects. The contemporaneous covariates of aggression, however, were not the same as the predictors, as determined by 3-month prospective follow-up. Twelve significant predictors were identified, and multiple regression analysis revealed different sets of measures that explain 45.0% to 52.5% of the variance for verbal, physical, and total aggression. The most reliable predictors were younger age, shorter length of illness, hostility, depression, anger, and difficulty in delaying gratification. We concluded that prediction is augmented by the combination of clinical and nonclinical predictors, and we discussed likely sources of disparity in previous research.