This paper discusses the four major types of test equating: (1) mean; (2) linear; (3) equipercentile; and (4) item response theory. The single-group, equivalent-group, and anchor-test data collection designs are presented as methods used for test equating. Issues related to assumptions and equating error are also addressed. The advantages and disadvantages of each equating method are discussed along with the conditions conducive to satisfactory equating. Research on the current interest in equating state tests to the Voluntary National Test or the National Assessment of Educational Progress is reviewed, and it is concluded that such equating is unlikely. (Contains 21 references.) (SLD)