Fundamentally, the goals of education are not unlike the goals of medical therapy; that is, to facilitate a desired change in an individual. In medicine, the prerequisite to the selection of any therapeutic regime is the diagnostic process — the identification of the antecedent states of an individual which must be taken into account in the attainment of the intended state. The educational analogue to the medical diagnostic process is the process of identifying the antecedent knowledge, skills, values or attitudes possessed by students entering a course which may influence the process of attaining, or the attainment of, the course goals. The educational analogue of the therapeutic regime are the instructional strategies which take the antecedent conditions into account and which are directed at the fulfillment of course goals. In education however, feasible methods have hot been identified for taking these antecedent conditions into account. In selecting teaching strategies in most classroom situations, it is not practical to take these conditions into consideration on an individual basis. Nor is it useful to consider class averages on these variables, since students vary so widely in terms of them. This study, working in the context of science education, and dealing with affective variables, developed a procedure for providing knowledge of antecedent affective variables in a form permitting their effective utilization in the process of selecting instructional strategies. More specifically, the purpose of this study was to develop a theoretically based and methodologically sound systematic procedure (generically "the Procedure") for (1) identifying, describing, and reporting the degree of pro-ness or con-ness of affective antecedents deemed to be important to science instruction and (2) identifying teaching strategies which take these antecedent conditions into account and which are directed toward science teaching outcomes in the affective domain. The general approach taken by the Procedure is to identify and describe subgroups of students within a class in terms of similar sets of antecedent affective responses to objects which reflect pro-ness or con-ness toward the affective ratings inherent in the affective goals of a course. Instructional strategies for these subgroups can then be selected or provide a rational basis for changing those antecedent ratings which are most incongruent with the desired affective ratings reflected in the affective goals. The affective goals are identified within a clear and accurate statement of the rationale for a course. Measurements of the degree of students' pro-ness or con-ness on the affective responses of concern are obtained through the use of the Semantic Differential technique. The Q-analysis technique, a technique for categorizing people, is employed to identify the subgroups of students. The educational value of the Procedure rests upon its ability to meet an important educational need in a practical way — specifically its ability to provide a clear description of affective antecedents in a form permitting their effective utilization in the process of identifying teaching strategies directed toward the fulfillment of affective goals. In this study, the results of the application of the Procedure to an introductory university physics course supported the general effectiveness of the contribution of each component of the Procedure in meeting this need. There is concern however (1) that additional data need to be gathered supporting the validity of the Procedure, and (2) that the time and monetary demands associated with the Q-analysis and Semantic Differential techniques might limit the feasibility of the Procedure in some educational settings. Recommendations and guidelines regarding future applications of the Procedure are provided, including recommendations regarding validity studies and the use of less costly alternatives to the SD and Q-analysis components.