Established in the 142,000-student Montgomery County, Maryland, district in 1999, peer assistance and review (PAR)--or "peer review," as it is occasionally called--is actually an old idea. In 1981, the then-president of the Toledo Federation of Teachers, Dal Lawrence, helped create the first PAR program. Almost 30 years later, only a handful of districts have followed the schools in that Ohio city with their own variations. But spurred on by new assistance primarily from the American Federation of Teachers, more districts are coming on board, even as the state of the nation's long-ignored, but much-criticized teacher-evaluation instruments rockets to the top of the national education agenda. Teacher experts are of two minds about the program's continuing expansion. Supporters believe that the stars have finally aligned to boost support for peer assistance and review. But other observers say that the program, which is intended for select subpopulations--novices and struggling veterans--should be more closely linked to an overall teacher-quality strategy for all teachers, including compensation reform. Timothy Daly, the president of the New Teacher Project, said peer review is an incomplete approach. It is a more collaborative way of doing what districts have been trying to do for decades--to detect incompetence. As the national conversation about teacher effectiveness continues, it is an open question how well peer review will fit into newly emerging systems.