In a program to facilitate the emergence of number conservation in preschool children, 45 middle class children and 64 Head Start and Title I children were trained to deal with perceptual confusions so that they could utilize this understanding to disregard irrelevant changes, such as spatial rearrangement, and thereby become aware of conservation of quantity. The children ranged in age from four to nine. The children were trained and tested under two experimental treatments for each of two conditions. In each age group, the children were categorized, on the basis of pretesting, as (1) conservers (who would receive no training), (2) nonconservers and transitional conservers (who would receive training), and (3) untestable. Incomplete data analysis indicated that middle class 7- and 8-year-olds were much better conservers, before training, than their Head Start peers. Both groups of children, however, at all ages, appeared to benefit greatly from the training sessions and were facilitated thereby in learning number conservation. (WD)