The present research has investigated Elkind's conceptual distinction between identity conservation and equivalence conservation. Although Piaget's description and analysis of conservation acquisition rests primarily on considerations of identity conservation, his assessment format has been exclusively equivalence conservation. The present argument contends that equivalence conservation subsumes identity conservation ability, but also includes a necessary logical deduction sequence for adequate equivalence conservation performance. Accordingly, identity conservation should be an earlier developmental acquisition than equivalence conservation. Appropriate settings were devised for identity and equivalence conservation assessment which equated the two conservation tasks in terms of perceptual cues and memory requirements. The tasks were administered, in a nonrepeated measures design, to equal numbers of males and females at the kindergarten, first, and second grade levels. A nonparametric multiple contingency analysis revealed that the main effects of conservation task type, age levels, and the sex dichotomy were significant. It was concluded that identity conservation definitely precedes equivalence conservation as a developmental achievement. Accordingly, Piaget's view of identity and equivalence conservation as simultaneous or concommitant developments is erroneous. Identity conservation cannot be adequately assessed in the conventional paired-stimulus format, and care should be taken in considering identity processes or explanatory concepts as a complete description of equivalence conservation achievement.