The U.S. Advisory Commission on Intergovernmental Relations (ACIR) befitted an era marked by low party polarization, bipartisanship, and cooperative federalism. Although the ACIR’s work was valuable, the growth of federal power, rise of party polarization, and the decline of bipartisanship, along with many other political, governmental, and social changes during its 37-year life (1959–96), marginalized the ACIR to the point of political vulnerability. These historic changes make it unlikely that the ACIR will be resurrected in a comparable or partial form.