The effects of teaching the logical sequence of steps assumed to be necessary for the attainment of conservation of number was evaluated in a series of three experiments using 130 kindergarten children. Part of the instruction was presented by slightly older conserving peers who acted as "assistant teachers." The experimental Ss showed significant growth in conservation while the control Ss showed no noticeable growth. The effects of the training were retained at three months and generalizability of these effects to conservation of discontinous quantity was demonstrated. No sex differences were found and only slight differences were revealed in conservation learning between SES groups. The importance of basic number concepts and language comprehension for the complete mastery of conservation through training is discussed.