The effectiveness of designated driver (DD) use in preventing driving while intoxicated (DWI) depends on whether drinkers at risk for DWI use DDs. Bivariate and logistic regression analyses conducted on data from 1,391 Computer-Assisted Telephone Interviews (CATIs) and from 902 barroom patron surveys showed that DD users, compared to nonusers, tended to be at-risk, heavier drinkers. For example, logistic regression using the CATI sample indicated that DD users were more likely to drink more often outside the home, to achieve higher blood alcohol concentrations (BACs) when drinking outside the home, to ride with intoxicated drivers (RID), and to be heavy drinkers on D. Cahalan et al.'s (1969) Quantity-Frequency-Variability (QFV) index. Similarly, logistic regression using the barroom sample showed that DD users tended to be heavy drinkers on the QFV index, and were more likely to drive after drinking and to ride with intoxicated drivers. Additional analyses showed that DD users also were more likely than nonusers to engage in other behavior to avoid DWI, such as drinking less, waiting to drive until the effects of alcohol diminish, walking home, and staying overnight. These results are consistent with other findings from a related study by the current authors which showed that at-risk drinkers also used free safe (taxi) rides to avoid DWI, however were still more likely to report DWI and RID behavior (B. D. Caudill, W. M. Harding, & B. Moore, in press). Consequently, DWI prevention efforts may be improved by future research aimed at learning why such at-risk drinkers sometimes take steps to avoid DWI and sometimes do not.