Health insurance purchasing cooperatives were established in the early to mid-1990s for the purpose of making health insurance more affordable and accessible for small employers. Extensive interviews at six cooperatives reveal that while some cooperatives enrolled large numbers of small employers, most have won only small market shares and a number have struggled for survival, not always successfully. They have allowed small employers to offer individual employees choice of health plans, but none has been able to sustain lower prices than are available in the conventional market. Among the important impediments to their success are limited support from health plans and conflicts over the role of insurance agents.