First Step Forward Act of 2007 - Amends the Juvenile Justice and Delinquency Prevention Act of 1974 to: (1) require information on the number of juveniles (under age 21) released from prison and their living arrangements upon release in the annual report of the Administrator of the Juvenile Justice and Delinquency Prevention Office; (2) require states seeking juvenile justice grants to adopt procedures to assure the availability of post-release programs and services for juvenile offenders; and (3) require research and evaluation on outcomes for juvenile offenders who have been released from custody and reintegrated into communities.

Directs the Attorney General to: (1) award grants to states to establish programs to identify juveniles likely to be released before attaining age 21 and to help such juveniles attain self-sufficiency; (2) develop outcome measures to assess the performance of states in operating juvenile offender reentry programs and track services provided to such offenders; and (3) conduct evaluations of state juvenile offender reentry programs.

Amends title XIX (Medicaid) of the Social Security Act to continue health care benefits for juvenile offenders after release from incarceration.