This study examines the factors driving the downward trend in employer sponsored insurance coverage between 1999 and 2002 for low- and moderate-income workers. We find that while low-income workers are more likely to be uninsured and are most vulnerable to the loss of ESI coverage, many middle income workers are also in a precarious position when faced with the loss of ESI coverage. The study also finds that the drop in ESI offers over the period was driven largely by changes in the nature of workers' jobs, while the drop in ESI take-up was driven largely by rising premiums. Health Services Research, Vol. 41, No. 6, 2006, pp. 2074-2096.