THE PROCESSES UNDERLYING THE REPORTING OF AN OBSERVED CRIME ASSUMES THAT BYSTANDERS ARE RATIONAL DECISIONMAKERS. AFTER SIGHTING AN UNUSUAL EVENT, THEY CALCULATE HOW DISCREPANT THE EVENT IS FROM PERSONAL NORMS, PONDER THE SORT OF LABEL THAT IS APPROPRIATE FOR EXPLAINING THE EVENT, ASSUME PERSONAL RESPONSIBILITY, AND ADD UP THE COSTS AND BENEFITS ASSOCIATED WITH ACTION. FINAL ACTION OR INACTION, THEREFORE, IS THE CONSEQUENCE OF A LONG CHAIN OF UNOBSERVABLE, COGNITIVE EVENTS. THIS ANALYSIS, HOWEVER, DOES NOT ALWAYS GUARANTEE THAT OBSERVERS WATCHING A CRIME WILL BE LOGICAL AND RATIONAL, OR EVEN THAT THEIR ULTIMATE ACTION WILL BE THE PRODUCT OF ANY DECISIONMAKING PROCESS. EMOTIONAL CONSIDERATIONS MAY INTERVENE AND OVERRIDE COGNITIVE FACTORS, SUCH AS THE FEAR OF CONFRONTING POLICE WHICH COULD INFLUENCE THE REPORTING OF EVEN A SERIOUS CRIME. THE MODEL DRAWS HEAVILY FROM CURRENT THEORIZING IN STUDIES OF HELP GIVING AND ALTRUISTIC BEHAVIOR. REFERENCES ARE GIVEN. (MJW)