This report assesses how the loss of Medicaid coverage following welfare reform has influenced changes in health care systems for immigrants in four urban areas: Los Angeles, California; New York, New York; Houston, Texas; and Miami, Florida. Survey data indicate that over half of low-income immigrants were uninsured in 1998, a level roughly double that of the native citizen population. Visits to each area in 1999-00 examined immigrants' access to insurance and health care services, changes in state and local policies and practices, and responses of local providers and agencies. All four areas have large health care safety nets, anchored by locally owned public hospitals and clinics. These public facilities were dominant providers of care for low-income immigrants, regardless of insurance status. In each area, states also elected to provide some additional coverage to immigrant children under the State Children's Health Insurance Program (S-CHIP). In some areas, outreach campaigns encouraged ethnic and immigrant parents to enroll their children in S-CHIP. Low-income immigrants' access to health care services was precarious before welfare reform and has weakened since then. Though many immigrants have turned to safety net providers offering free or reduced price care, they have also delayed or avoided medical care and turned to alternative, sometimes underground, health care providers for services. State and local government actions and safety net providers have cushioned the effects of federal policy changes, but such efforts may not be sustainable as the number of immigrants ineligible for Medicaid grows. (Contains 32 references.) (SM)