The relationship between conservation and achievement is examined on specific tests and test items on the Stanford Achievement Test Battery used in the elementary years. Specifically, performance on two tests (Word Meaning and Arithmetic Concepts) were analyzed according to subjects level of thinking (concrete or formal) for total score, individual items, number of items omitted, IQ, and sex. The subjects were 48 fifth-graders ranked according to IQ scores, with an equal number of males and females at each IQ score (range from 82 to 150) and ranging in age from 10.33 to 12.42 years (average 10.96). In addition to the Stanford Achievement tests, tests of conservation were administered individually, using Piaget's traditional clay tasks first and then Lovell and Ogilvie's (1960) procedure for testing conservation of volume using solids, bricks and water. Subjects were classified on the formal level if they met Piaget's criterion of formal level on the clay task and Lovell and Ogilvie's criterion for the conservation of volume tasks. Subjects were classified as concrete if their judgments were based on perceptual differences rather than understanding of abstract relationships. A Chi Square test of independence between level of thinking and achievement test performance showed superior performance by those on the formal level on total score for Word Meaning and Arithmetic Concepts. (Author/DB)