Curriculum materials and knowledge about curricular purposes and structures are valuable tools that teachers often draw upon to organize instruction and facilitate student learning. Careful analysis of teachers' curriculum implementation and the decision-making that undergirds their curriculum use is critical for fully understanding enactment. This paper compares how "integrity analyses" of implementation of curriculum materials and "actor-oriented analysis" of teachers' curriculum use can help researchers, teacher educators, and curriculum designers interpret teachers' decisions about what aspects of new materials to use and how to use such materials. Drawing on evidence from teacher interviews and observations, we compare two teachers' enactments of a new elementary-level environmental biology unit. Our analyses of integrity point to differences in teachers' adaptations with respect to their consistency with the purposes and structures of curriculum materials as construed by designers. By contrast, our actor-oriented analysis explain how the teachers' different approaches to interpreting the goals and structures of the curriculum unit partly account for patterns in their enactment in ways that can inform refinements to materials and the design of professional development supports for teachers. In so doing, we show how implementation integrity and actor-oriented analyses offer complementary perspectives to inform curriculum research and development.