From the perspective of prosocial behavior, bystander intervention is conditioned by situational factors; from an informal social control perspective, bystander intervention has been demonstrated to be associated with level of crime and violence at the community level. This study shows that fear of crime and type of community have robust and consistent effects on bystander intervention, controlling for demographic characteristics including sex, age, and education. The implications of the findings are discussed in terms of bystander intervention as both prosocial behavior and informal social control. The findings also question the usefulness of simply casting bystander nonintervention as corrupted morality in China. Tables, notes, and references (Published Abstract)