The crackdowns involved an abrupt and marked increase in drug law enforcement activity that was to be sustained over 6 months, using existing resources with differential deployment and administrative emphasis. The crackdowns focused on four geographic areas, two during the first 6-month period and the other two during the second 6-month period. Study data came from official records, observations of enforcement activity, interviews of Narcotics Division officers and supervisors, surveys of community residents, and interviews with a panel of persons knowledgable about the communities. Implementation of the crackdowns was more difficult than anticipated. Nevertheless, enforcement activity was intensified and sustained for some time. However, the effects on drug markets did not translate into effects on predatory crime or residents' perceptions of the quality of life. Findings suggested the desirability of shorter and more intense crackdowns, the creation of a unit dedicated to crackdown activity, the use of information to formulate a strategic approach, and the integration of drug law enforcement strategies into community policing. Figures, tables, footnotes, and 46 references