Describes a two-year demonstration project, funded by the California Endowment, to subsidize health coverage for uninsured, low-income, undocumented immigrant children in California. More than 7,500 such children received health insurance coverage through four nonprofit health plans and one nonprofit organization that purchases health coverage for children. Among the lessons learned were that: (1) multiple outreach and enrollment activities were crucial to serving the target population effectively, and a recommendation from a trusted source was the most effective referral method; (2) effective methods of reducing enrollment barriers included simple application forms and assistance in the applicants? language; and (3) continued outreach and case management were essential to maintaining contact with a highly mobile membership. Rapid enrollment in these subsidized programs reflected a high level of need; however, sustaining and promoting coverage for uninsured, undocumented immigrant children will require substantial resources and support from multiple stakeholders. In particular, funding partnerships with statewide and local public and private sources may help ensure the most sustainable results. These partnerships will be instrumental in supporting the growing number of California counties that are providing health insurance coverage for all low-income, uninsured children without regard to residency status. (IP)