AUDs are increasingly recognized as common problems among older adults. The magnitude of this problem is likely to increase over ensuing decades as baby boomers reach retirement age with drinking habits that are significantly different from current cohorts of older adults. Barriers to detection are numerous and include nonspecificity of alcohol-related presentations, patient denial, and clinicians' unwillingness to recognize that patients can and do develop alcohol problems in later life. Despite the limitations of current screening and diagnostic instruments, the authors recommend use of the CAGE as a formal screening tool for older patients because of its brevity, demonstrated efficacy, and convenience. In patients who answer affirmatively to any CAGE question, diagnostic certainty can be increased by use of follow-up questions or referral to an alcohol treatment specialist. Referral of patients with established alcohol abuse or dependence is essential for definitive treatment, and successful outcomes can be expected and are gratifying once achieved. In patients with less severe AUDs, brief interventions with frequent follow-up are recommended. Age-specific screening and diagnostic instruments for older AUD patients, once fully developed and validated, will facilitate identification. Much less is known about other substance use disorders in older adults. Psychoactive drug use is not uncommon in this patient population and may result in adverse health outcomes. Treatment interventions proposed for AUDs are advocated for older adults found to have other substance use disorders as well and are likely to yield improved outcomes. Future investigations that better define the epidemiology, detection, and treatment of other substance use disorders in older populations are clearly warranted at this time.