Between 2001 and 2003, both children and adults lost employment-based health insurance coverage. For children, increased enrollment in Medi-Cal and Healthy Families resulted in a lower uninsured rate. For adults, however, the decline in employment-based insurance coverage from 2001 to 2003 resulted in a slight increase in the uninsured rate. Using data from the 2003 California Health Interview Survey, this policy brief provides a profile of nonelderly Californians' health insurance coverage and describes how these rates have changed since 2001. In 2003, 6.6 million nonelderly Californians were uninsured at some time during the year -- the majority of whom were uninsured for at least the entire year. In fact, one in four nonelderly adults and one in ten children under age 18 experienced a lack of coverage for all or part of the year. In addition, this study found that three-fourths of uninsured nonelderly Californians are in working families. Over 80% of uninsured employees have no access to employment-based insurance coverage because they either worked for an employer that did not offer health insurance, or they were not eligible for benefits from their employer. While more than half of uninsured children in California were eligible for enrollment in Medi-Cal or Healthy Families, only 6% of uninsured nonelderly adults, ages 18-64, were eligible for these public programs. Overall, rapidly rising health insurance costs and a still-slack labor market have reduced employment-based insurance in California since 2001. However, Medi-Cal and Healthy Families have proven their effectiveness in covering children, underscoring their potential for offsetting at least some of the loss in job-based insurance.