"Testing for Justice Rationale" calls for schools to meet the needs of all children. The needs of children can be determined by comparing what children can do with what they can learn to do. Any discrepancy between achievement and potential indicates a need and it is only through adequate testing that these needs can be determined. This article discusses how Testing for Justice Rationale burdens testing with determining not only need but, ultimately, justice as well. The author also discusses the importance of consensus on the methods of determining student knowledge independent of the test. (Contains 3 charts and 13 notes.)