The science curriculum model developed for the American Association for the Advancement of Science (AAAS) as Science - A Process Approach is used to analyze two units of Elementary Science Study (ESS). An "ESS hierarchy" was developed from an analysis of the ESS units, and the resulting behavioral statements were organized into seven levels according to criteria used in Science -A Process Approach. This effort also resulted in the development of an experimental process measure for ESS. Twenty-one teachers administered the revised process measure and content test to their classes during the year 1966-67. The process measure was administered to five children in each of 11 classrooms before they studied the ESS units. This same process measure was again administered toward the end of the year in 16 classrooms to different students also randomly selected. A content test was also administered at this time to these same students. An improvement in performance after studying the ESS units is indicated as measured in terms of transfer to another context and as transfer within the behavioral hierarchy or between learning sets. Gains on the content test were not significant. (BC)