Objective: College students tend to drink while serving as a designated driver (DD). The predictors of alcohol use by DDs among college students were examined. Participants: Participants were 119 undergraduate students in introductory psychology courses who had experience with DD use. Methods: Survey data were analyzed to examine the predictors of planning components of DD use, such as choosing a DD before drinking and choosing an abstinent DD, and the relations of these components to alcohol use by DDs. Results: History of DD use, friends' willingness to be the DD, frequency of riding with a driver who drank and drove, and age of drinking onset were associated with planning components of DD use. Among the planning components of DD use, choosing a DD before drinking was significantly related to less alcohol use by DDs. Conclusions: Increasing awareness of the planning components of DD use could deter alcohol use by DDs among college students. (Contains 2 tables and 1 footnote.)