The clinician needs to stay informed about the groups he or she treats and be sensitive to their special nature. The groups discussed below are intended to be representative of those populations the clinician is most likely to encounter, and whose unique issues in relation to substance abuse merit a specific, brief discussion. There are a few very important populations that naturally stand out in terms of their special needs as pertains to substance abuse treatment issues. Persons interested in substance abuse and its treatment are advised to be aware of the special needs of specific populations encountered. The following are offered as a smattering of some of the most germane "special" populations.