Streptococcus pneumoniae is the most common cause of bacterial pneumonia worldwide and a leading cause of sepsis and meningitis. In the United States, an estimated 40,000 persons die each year from pneumococcal infections. Since 1983, 23-valent pneumococcal polysaccharide vaccines have been licensed in the United States and are 56%-57% effective in preventing invasive pneumococcal disease. However, the 1993 National Health Interview Survey documented that < or = 28% of persons in high-risk categories, including all persons aged > or = 65 years, reported ever having received the vaccine. During 1993-1994, VHA Inc. (Irving, Texas)--a national health-care alliance serving approximately 1200 health-care organizations nationwide (including 21% of all community hospitals in the United States)--initiated efforts to improve pneumococcal vaccine delivery to and coverage among patients at increased risk for complications of pneumococcal infection. This report summarizes the program and an evaluation of its effectiveness in increasing vaccine coverage.