This study investigates the effects of a training procedure on children's conservation. Volume conservation was induced in twenty-one 8-year-old non-conserving children by a procedure that combined two sources of conflict. First, the competing schemes used in making decisions on volumes were aroused; second, the non-conserver was made aware of a conserving peer's judgments at strategic points in the training. The training effects were specific to the conservation of quantity, weight, substance and interior volume. These concepts depend on the assimilatory schemes brought into conflict by the training program. The findings suggest that training based on conflict arousal between schemas, and made more salient by peer interaction is an effective stimulant to development. (Author/MP)