A study was conducted to determine whether a significant correlation exists between developmental age and the concept of conservation. The hypothesis was that if developmental age and the concept of conservation are related, then stages of understanding conservation will increase as developmental age increases. Ss consisted of 30 primary children from a school using placement based on Gesell developmental levels. Ss were tested on a one-to-one interview basis with six Piagetian tasks concerning conservation of quantity and the Gesell Developmental Examination, which consisted of an initial interview, paper and pencil tests, right and left tests, form tests, naming of animals, concluding interview, and examination of teething progression. A relatively high relationship was found to exist between the two variables, but not high enough to use for predictive purposes between the two instruments. Uses of the instruments are discussed, and it is recommended that the curriculum for primary children even in a developmental-placement school be highly individualized. (KM)