This article explores how one specially prepared, accomplished teacher managed dilemmas that arose as she worked to enact responsive language arts instruction with English Learners in a policy context that privileged high-stakes accountability and standardization. Drawing on sociocultural learning theory, the article illustrates how the teacher's sense of self--who she "wanted to be"--informed her engagement with educational policy. Ultimately, we argue that the teacher's identity pressed her to engage in acts of appropriation and authorship vis-à-vis the policies and policy-related tools she was asked to implement. In making this argument, we theorize an agentive and dialectical relationship between teachers' identities and their participation in policy implementation.