Many studies of the reasons people select teaching as a career have used quantitative instruments featuring a checklist of reasons one might enter teaching to which subjects respond using a checklist or a continuously scaled Likert format. In this study, results of an effort to establish the construct validity of such an instrument are reported. A 58-item instrument was developed based on previous instruments and on ideas germane to theories of career motivation found in the literature. The items were initially categorized according to eight career-motivation orientations found in the literature. The subjects (n=255) included both teacher education students and inservice teachers. Responses were factor analyzed using both oblique and orthogonal rotations. Several factor solutions were attempted, and a six-factor orthogonal solution deemed the most interpretable. The eight proposed motivational orientations were roughly evident in the interpreted factors. Suggestions as to how the instrument may be substantively applied in teacher education research are offered. An appendix lists the items in the instrument. (Contains 10 references.) (Author/SLD)