A study was conducted at Essex Community College (ECC) to test the validity of the Modified Kenny-Griffiths Test for Formal Operations, a paper-and-pencil instrument designed to determine the cognitive level of incoming adult students. The test sample consisted of 100 students (50 male and 50 female) who were equally divided between physical and social science majors. The instrument asked the students to indicate their age, sex, and major and to complete a series of problems designed to place them within three cognitive levels defined by Piaget: (1) the formal stage, at which an individual can use hypothetical reasoning; (2) the concrete operations stage, at which the individual can deal only with relationships between real, sensed objects; and (3) the pre-operations stage. As a test of the instrument's validity, the same students were administered Piaget's "Combination of Colorless Chemical Bodies" task. Correlations between the subjects' scores on the written test and the Piaget task were statistically determined, as were the influences of sex, age, and major on study outcomes. The study report discusses cognitive development and practical aspects of its measurement, Piagetian theory and its limitations when applied to collegiate learning, the need for diagnostic testing at ECC, and the lack of formal operations in adult learners. It also describes study procedures, methodology, and findings. Two versions of the test instrument are appended. (JP)