Third World countries have used community health advisors (CHAs) for many years to deliver health services, health education, and linkages to isolated and underserved communities. In 1998 the National Community Health Advisor Study estimated there were at least 600 such programs in the United States using about 12,500 CHAs. Program activities and target populations vary widely; CHAs' work ranges from volunteer service in health education to actual provision of services. The most significant commonalities of CHA programs are a focus on reaching hard-to-reach populations, use of indigenous workers, and CHA expertise in community knowledge rather than formal education. Results of the 1998 national survey of 281 respondents provided data on rural and urban location of programs, racial and ethnic groups targeted, types of health problems encountered, provision of advocacy services, and types of outreach sites. Most CHAs were paid workers but averaged only 20 hours per week. Examples illustrate typical CHA activities: (1) acting as a bridge between underserved people and service providers (explaining the system to clients and gathering information for providers); (2) providing culturally appropriate health education and information; (3) locating cases, making referrals, and providing followup; (4) helping people with basic needs; and (5) building individuals' capacity to help themselves. Only a few evaluations of CHA programs have been carried out, all with positive results. Serious challenges for programs include inadequate and unreliable funding, lack of legitimacy among professionals, the health care system's lack of emphasis on prevention, and varying levels of CHA training. Recommendations focus on formal recognition of the value of CHAs, better funding, a comprehensive evaluation, and advocacy. (SV)