The purpose of this paper is to introduce a Q-sort type instrument which is useful for obtaining descriptive information about teaching methods and curriculum materials used in the science laboratory. This instrument, The Laboratory Program Variables Inventory (LPVI), was used in a series of experiments investigating laboratory formats used in college general chemistry courses. Three possible formats were investigated: (1) verification laboratories, (2) guided inquiry laboratories, and (3) open/guided inquiry laboratories. Using several data analysis techniques, LPVI data were used to operationally define the three formats and identify specific criteria for discriminating among them. The use of the Q-sort, in general, and the LPVI specifically, might fulfill a number of evaluation needs in science education including: (1) developing operational definition of constructs (e.g., “inquiry”), (2) diagnosing problems in curriculum development or implementation, (3) rationalizing differences in treatment groups in educational experiments, and (4) monitoring the effect of teacher education efforts.