The major question this study attempted to answer was, "Can conservation of number, area, weight, mass, and volume to be induced and retained by 3- and 4-year-old children by structured instruction with a multivariate approach? Three nursery schools in Iowa City supplied subjects for this study. The Institute of Child Behavior and Development contributed 80 children; the University Parents Cooperative Pre-school contributed 52; and Iowa City Montessori Nursery School furnished 53. The Institute was selected as the control group; the University Parents Cooperative Pre-school comprised the experimental group, and the Montessori Nursery School children were used for the pilot study. An individual Stanford-Binet Intelligence test, a criterion pretest, and a posttest were administered. Criterion scores were based on one of two equivalent forms, each containing a 57-item conservation test, one test of rote counting, one test of rational counting, and a rating of attentiveness. The experimental group showed a significant gain over their own pretest scores in every subtest except one. The analysis indicated that gains by the experimental group in 16 of the 17 subtests were significantly greater than gains by the control group. The results showed conclusively that the concepts could be learned by 3- and 4-year-old children. (DO)