The one-year prevalence of use of psychotropic medications among youths enrolled in a Mid-Atlantic State Children's Insurance Program (SCHIP) in 1999 or 2000 was compared with the 1998-2000 prevalence findings for youths enrolled in four large multistate private medical insurance programs. Prevalence was significantly higher among youths enrolled in the SCHIP than among those with private insurance in all eight medication group comparisons. Unlike private insurance, the surveyed state SCHIP program did not require a copayment or have a restrictive formulary. These administrative differences may partly explain the comparatively higher rate of psychotropic use under the SCHIP.