When fully implemented, the Affordable Care Act will expand insurance coverage to the currently uninsured, and experiments in delivery and payment under the law's auspices could produce greater efficiencies in how care is delivered. Both factors may accelerate the development of one viable model to streamline care, integrated delivery systems--coordinated care networks that deliver all needed health services to a defined population. Through interviews and surveys, we examined ten California counties that participated in two federally and locally funded initiatives to redesign how care is delivered to predominantly poor and uninsured populations. We found substantial progress in assessing and managing access to specialists, monitoring and promoting quality, and offering disease management and care coordination training in a majority of counties. However, efforts to coordinate care, electronically disseminate patient information, and align financial incentives were less successful or more difficult to assess. We posit that integrated delivery systems could improve care efficiency and quality and make countywide safety-net systems a desirable source of care for newly insured patients under health reform.