The effects of advance organizer instruction on the acquisition of number, mass, area, quantity, and length conservation concepts in 3- and 4-year-old children are examined. Participating in the experiment were 28 children, a total of 14 in respective experimental and control groups. All children were pretested and determined to be nonconservers. A sequence of two advance organizer lessons was presented to the experimental group: the first concerned paying attention to special properties of objects, while the second focused on use of high-order rules for solving conservation tasks. Control group children received regular instruction in a preschool program using a guided-discovery method of instruction. Posttests were conducted immediately after the training period, to measure immediate transfer of training, and after about 4 weeks, to measure long-term retention of conservation concepts. Results indicated that advance organizer instruction was successful in promoting the learning of a high-order rule for conservation that children generalized to the five conservation concepts. The high level of improved performance by the experimental group at the first posttest was maintained at the second posttest. Control group children showed little improvement in performance in either posttest, and their level of performance remained essentially preoperational. (Author/MP)