Viewpoints within the general perspective that the prediction of dangerousness is not possible are that (1) no objective, empirical evidence exists for clinical predictions at acceptable levels of reliability and validity (psychiatric expertise not demonstrable); (2) dangerousness can be defined by factors other than prediction so as to assist in sociopolitical decisions (psychiatric expertise not decided yet); and (3) mental disorders manifesting certain impairments can produce a potential for harm, and the impairments of mental disorder copresent with past violent behavior can be identified (psychiatric expertise demonstrable). Viewpoints within the general posture that prediction of dangerousness is possible are that (1) clinicians are already intuitively identifying dangerous persons (psychiatric expertise not demonstrable); (2) not all of the data is in, and current studies of prediction lack validity (psychiatric expertise not decided yet); and (3) perimeters do not exist that can aid clinicians in identifying dangerousness (psychiatric expertise demonstrable). Standards for assessing dangerousness include actualities (substantial thrests of physical harm or violent acts that can be observed and reported as facts), unacceptable thresholds (certain situations can be deemed sufficiently dangerous to justify some involuntary restrictions or treatment), and potentialities (any conceivable risk associated with a mental dysfunction under circumstances of inadequate supervision or treatment may be considered). Different models for deciding dangerousness are used in the circumstances of civil commitment, hospital discharge for mentally disordered offenders, emergency treatment, and professional negligence. A bibliography of 36 listings is provided.