Scotland is one of several countries to have recently implemented a new national curriculum to highlight 21st century educational priorities. Teachers have been mandated to follow the new curriculum guidelines, known as Curriculum for Excellence (CfE), since the fall of 2010. The purpose of this study was to use a phenomenological lens to investigate how Scottish secondary science teachers are experiencing their work of curriculum development, including daily lesson design and more broadly, curriculum mapping within the context of reform (Remillard [1999], "Curriculum Inquiry," 29: 315-342). We probed seven science teachers' experiences to create both a composite profile of conscious thoughts about curriculum design and individual profiles that highlight interactions between the curriculum mandates, beliefs, and agentic orientations. The study indicated that changes to curriculum development required accepting new cognitive commitments including: (i) analyzing the CfE document to discern the most significant principles underlying change; (ii) reflecting on the ways that science teacher curriculum development is a problem-solving endeavor; (iii) undertaking the complex processes of curriculum mapping, from primary school all the way through national qualification exams; and (iv) recognizing that the epistemological frame for students' science learning has changed and providing opportunities for students to create and apply knowledge. Two significant findings include the unpacking of these cognitive activities as part of a transformation toward a new epistemology of pedagogy, and the assertion that official curriculum documents can promote change, albeit with caveats concerning individual beliefs, agentic orientations, and possibilities for agency within school contexts.