This paper examines the extent to which the State Childrens Health Insurance Program (SCHIP) might be substituting for private health insurance coverage at the time of enrollment. Among children who were newly enrolled in SCHIP in 2002 in ten states, about 14 percent had private coverage that they could have retained as an alternative to SCHIP. Of this 14 percent, about half of parents reported that the private coverage was unaffordable compared with SCHIP. This suggests that relatively few SCHIP enrollees could have retained private coverage and that even fewer had parents who felt that the option was affordable.