This study examined the relevance of these models for explaining patrol officers' decisions to arrest in the drinking-driving situation in four police agencies. Analysis of officer questionnaire responses (N=71) to a drunk driver scenario showed that officers in the two larger, bureaucratized departments were much less likely to arrest than those in the smaller departments. Loose coupling of the administrative apparatus and officer discretion were pronounced in the large departments, but administrative priorities were closely coupled to officer discretion in the small agencies. Unable to employ elaborate bureaucratic forms due to size constraints, the small departments pursued DUI arrests to demonstrate their professional worth. The larger departments, operating with fewer resources relative to demand, were preoccupied with other issues and did not find a high DUI arrest rate particularly useful for sustaining community support. They were able to rely on institutional forms that signified commitment to DUI arrests without actually constraining officers to make them. (Author abstract)