Teachers and teacher educators in the US struggle with conflicting needs. They must think critically and adaptively in response to the rapidly changing demographics of their students and adjust to a policy climate that emphasizes standardization, measurement, and disregard for teachers as professionals. Embattled pre-service teacher education programs in institutions of higher education have traditionally sought to develop teacher candidates’ knowledge, skills, and dispositions. The authors argue that in the current climate pre-service teachers also must appropriate conceptual frameworks to support (...) their development as responsive professionals. While dispositions are beliefs and attitudes the origin and teaching of which remain in dispute, concepts like social justice, political-economic equity, and formative assessment are abstract ideas or concepts that inform practice. Conceptual tools, i.e., concepts, theories, and frameworks, guide novice teachers in making decisions in response to the growing and rapidly changing student populations they will teach as well as the policy contexts that constrain their teaching practice. The appropriation of conceptual tools contributes to development of vision and adaptive expertise required by responsive teacher professionals. Using an activity theory framework developed by Wartofsky that draws in particular on the classification of artifacts, or tools, this article frames and critically examines teachers’ need for conceptual tools, the appropriation of those tools, and a mixed methods study of that appropriation. The study demonstrates that teacher candidates do appropriate conceptual tools, but that measurement of that process, though desirable in the current policy context, requires the development of a systematic and replicable methodology. (shrink)