This paper presents two years of analysis of a professional development effort in an urban district in Arizona in the wake of policy requirements to track students by language proficiency level, mandate four hours of English Language Development each day, and focus on teaching grammatical structures. The professional development focused on Cognitively Guided Instruction, which centers mathematics instruction on the informal knowledge students bring with them to schooling to build meaning, sophistication, and understanding of the mathematics. Results indicate that before the policy, professional development produced more teacher experimentation than after.