THE LITERATURE INDICATES THAT, WHILE THE CONCEPT OF DANGEROUSNESS IS BECOMING INCREASINGLY IMPORTANT IN THE CRIMINAL JUSTICE AND MENTAL HEALTH SYSTEMS, DANGEROUSNESS CANNOT BE PREDICTED ACCURATELY AND USUALLY IS OVERPREDICTED. IN CALIFORNIA, POLICE ARE AUTHORIZED TO MAKE EMERGENCY APPREHENSIONS OF PERSONS WHO SEEM TO PRESENT A DANGER TO THEMSELVES OR OTHERS OR WHO SEEM TO BE GRAVELY DISABLED BECAUSE OF A MENTAL DISORDER. SUCH PERSONS MAY BE SCREENED AT DESIGNATED MENTAL HEALTH FACILITIES, WHERE THEY MAY BE CONFINED INVOLUNTARILY FOR 72 HOURS FOR EVALUATION AND TREATMENT. TO ASSESS THE PROCESS OF EMERGENCY APPREHENSION AND SCREENING IN SANTA CRUZ, 34 POLICE OFFICERS AND 6 MENTAL HEALTH CENTER CRISIS INTERVENTION WORKERS (SCREENERS) WERE OBSERVED AND INTERVIEWED, AND POLICE AND SCREENING REPORTS ON 196 CASES WERE REVIEWED. BOTH POLICE AND CRISIS INTERVENTION WORKERS SEEMED TO VIEW DANGEROUSNESS AS A TRAIT OF THE INDIVIDUAL; I.E., TO LABEL THE PERSON RATHER THAN THE PERSON'S BEHAVIOR AS DANGEROUS. POLICE TENDED TO MAINTAIN AN AUTHORITARIAN STANCE IN EMERGENCY APPREHENSIONS, TREATING THE INDIVIDUAL THE SAME AS ANY OTHER ARRESTEE. CRISIS WORKERS SEEMED SOMEWHAT MORE ORIENTED TO A PARENS PATRIAE ATTITUDE TOWARD EMERGENCY DETAINEES. HOWEVER, POLICE AND CRISIS INTERVENTION WORKERS WERE MORE SIMILAR THAN DISSIMILAR. BOTH WERE CONCERNED WITH THE PROTECTION OF SOCIETY AS WELL AS THE WELFARE OF THE INDIVIDUAL. THEIR SHARED OBJECTIVE WAS TO DETAIN POTENTIALLY DANGEROUS PERSONS UNTIL SOMEONE MORE QUALIFIED COULD MAKE THE ULTIMATE DECISION. THE ATTRIBUTION OF DANGEROUSNESS APPEARS TO BE A COMPLEX PROCESS INVOLVING MANY VARIABLES ASSOCIATED WITH SOCIAL CONTEXT, THE DECISIONMAKER, AND THE DETAINEE. BIZARRE BEHAVIOR AND PSYCHIATRIC HISTORY WERE MORE STRONGLY RELATED TO THE LIKELIHOOD OF PSYCHIATRIC CONFINEMENT THAN ANY OTHER VARIABLE STUDIED. INTERVIEWS WITH CRISIS INTERVENTION WORKERS INDICATED THAT THE WORKERS THEMSELVES FELT THAT THEY OVERPREDICTED DANGEROUSNESS. POLICY AND RESEARCH IMPLICATIONS OF THE FINDINGS ARE DISCUSSED. SUPPORTING DATA, A LITERATURE REVIEW, AND A LIST OF REFERENCES ARE INCLUDED.