H.R.3584: To amend title XXI of the Social Security Act to extend funding for 18 months for the State Children's Health Insurance Program (SCHIP), and for other purposes.

SCHIP Extension Act of 2007 - Amends title XXI (State Children's Health Insurance) (SCHIP) of the Social Security Act (SSA) to: (1) extend SCHIP through FY2008 and the first six months of FY2009; (2) provide additional allotments to states to address SCHIP funding shortfalls for the same period of time; and (3) authorize qualifying states to elect to receive the enhanced portion of the SCHIP matching rate for coverage of certain children under SSA title XIX (Medicaid).