This policy brief highlights the differences in uninurance rates among the new California Assembly and Senate districts resulting from redistricting based on the 2000 Census. Funded by The California Endowment, this report is particularly relevant at this time when the lack of health insurance has moved higher on political agendas at the state and national levels. Uninsured rates at the district levels are estimates created by a small-area-methodology with data from 2001 California Health Interview Survey (CHIS 2001), the March 2000-2002 Current Population Surveys, and the 2000 Census. This first-of-its-kind information contributes valuable and timely data needed by California’s community and health advocacy groups as well as legislators to support their respective policy development roles and to inform and focus their efforts on high-priority health and medical care issues, locally and statewide. In addition to the data presented in this policy brief, several supplemental California Assembly and Senate exhibits (tables and maps) are available on this Web site: maps by district of uninsured rates for children (ages 0-17) and for adults (ages 18-64); demographic tables of district population distributions by race/ethnicity and income-to-poverty ratios; and confidence intervals (or precision estimates) for the published uninsured rates. Among the key findings are: Rates of uninsurance are particularly acute in legislative districts located in the Central Valley and in Southern California. There are substantial geographic disparities in health insurance coverage for children and adults among the newly redrawn California Assembly and Senate districts. Legislative district uninsured rates range from a low of 7% for children ages 0-17 in Assembly District 15 to a high of 50% for adults ages 18-64 in Assembly District 46. Even the districts with the lowest rates of uninsurance have a considerable number of uninsured residents. For example, Assembly District 15 has 38,000 uninsured persons under age 65, and the Senate District with the lowest rate of uninsurance (SD 7) is home to 78,000 persons under age 65 who have no insurance. Key Policy Recommendation More extensive outreach efforts must be implemented to ensure that all children and adults who are eligible for public programs get enrolled into them. The findings in this brief identify the locations in the state where outreach and enrollment efforts can be most effective.