Since 1987 the Health Insurance Association of America (HIAA) has documented features of employer-sponsored group health insurance through detailed surveys of over 3,000 U.S. firms. The 1991 employer survey reveals several noteworthy developments. The percentage of small firms (100 employees and under) that offer health insurance to their employees has declined since 1989. With a significant increase in health maintenance organization (HMO) market share, more than half (54 percent) of employees in employer-sponsored plans are now covered by managed care plans. Premiums increased 14 percent in 1991, showing identical increases for conventional, HMO, and preferred provider organization (PPO) plans. The percentage of employees in self-insured health plans decreased from 45 percent in 1990 to 40 percent in 1991.