Although some view predictions of dangerous behavior to be impossible or inappropriate, these predictions are often made. Although it is currently impossible to make accurate predictions, they carry major implications for the adolescent and for society. Nevertheless, several types of factors have been found to be the most objective and rational in making these decisions. Clinical decisions currently dominate the law. Personality factors and motivational concerns are the most significant of the clinical factors. Research has also focused on the way that clinicians go about the prediction process. The use of statistical information is controversial, although it can enhance the clinical decisionmaking process. The most important factors in statistical prediction of violence are past violence, age, sex, race, socioeconomic status, and alcohol and drug abuse. Particularly important situational factors are the family environment, the peer environment, the job or school environment, availability of victims, availability of weapons, and availability of drugs or alcohol. These environmental variables may have a stronger role in future predictions. For prediction models and practices to become more effective, the linkages between the legal and mental health professionals making the decisions need to improve. Twenty-three references are supplied.