The purpose of the current study was to examine differences in responses of older adults (age 55 and above) and younger adults (ages 18 to 54) to the Drug Abuse Problem Assessment for Primary Care (DAPA-PC), a computerized drug and alcohol abuse screening instrument developed for primary care settings. Data were collected from a diverse population of 327 adults presenting for care at The George Washington University Medical Faculty Associates clinic in downtown Washington, DC. Results indicated that rates of drug and alcohol abuse were similar in both groups. However, older adults were less likely than younger adults to perceive their drug use as problematic. This finding has serious implications for older adults, who tend to be underrepresented in treatment programs. There is a need for screening seniors and identifying those who may be at risk for substance abuse problems. Differences in responses to alcohol and drug assessments by age should be taken into consideration when designing screening instruments. The results of this study suggest that the DAPA-PC would provide a useful instrument for screening older adults in a primary care setting.