Children's enrollment in the State Child Health Insurance Program (SCHIP) is a key indicator of program impact. Past studies demonstrate that many children eligible for Medicaid or for private employer-based insurance remain uninsured, indicating that eligibility does not guarantee either enrollment or access to medical care. Important features of SCHIP evaluation include not only eligibility thresholds and enrollment volume, but also program retention, transitions in coverage, and access to medical care. Focusing on SCHIP features that affect children's participation and continuity of coverage would allow states to continually improve procedures that affect enrollment. An exploration of federal and state policy options suggests several approaches for creating evaluation strategies that can stimulate ongoing improvement.