Sustainability, though not well understood, is an increasingly important concept in society, and as such has become incorporated in school curricula. In New Zealand, sustainability was added to the national curriculum in 2007 as a non subject-bound thematic link through the values and key competencies associated with student learning. Teachers use the national curriculum, a statement of policy describing educational objectives, to plan their classroom practice with their particular learners in mind, a process referred to as local curriculum development. Though sustainability education is new to New Zealand teachers, there is a strong history of environmental education where implementation has been successful in many primary schools, in which the curriculum is integrated. In the secondary school setting, the implementation of non subject-bound learning, like environmental education, has proven to be less successful, partly due to the siloed nature of subject specialisation. Sustainability as the interaction between environmental, social and economic perspectives has proven to be particularly difficult to address in such siloed secondary schools. This study investigates the sense making practices of some English, science, social science and technology secondary teachers as they interpret sustainability in the national curriculum and create local sustainability curricula in their school settings. The research occurred three years after the introduction of the revised national curriculum and at a time when few professional learning opportunities existed to support teacher professional development. The research is founded on sociocultural learning theory drawing on concepts of mediated action, and situated and distributed cognition. Research data was generated over a year-long collaborative action research programme and analysed using Cultural Historical Activity Theory as a tool. The findings indicate that these teachers were challenged by the siloed nature of curriculum delivery in addressing the holistic nature of sustainability in their local curriculum development. Teachers’ personal sociocultural backgrounds were influential in their sustainability curriculum development practices. These experiences influenced their perspective of sustainability, often limiting their perception of sustainability. These perspectival views of sustainability had direct influence on teacher’s curriculum development, constraining planned learning in sustainability to their perspective. Where teachers worked independently in their school to develop local curriculum their perspectives went unchallenged, resulting in local curricula that addressed only parts of the nature of sustainability. Teachers’ perspectives of sustainability also influenced their ongoing professional learning choices in a conservative manner. Without intervention, this self-reinforcement of existing perceptions may lead to strengthening curriculum silos and further constrain sustainability education. Where teachers worked collegially across curriculum silos, and had opportunities to negotiate meaning around sustainability and sustainability education in the wider culture of the school, their perceptions of sustainability become more comprehensive, leading to local sustainability curricula which reflected more fully the holistic nature of sustainability. Meaning making around sustainability and sustainability education, in the culture of the school, includes considering how sustainability is expressed in the national curriculum, what is meant by assessment of learning in sustainability, the role of students in curriculum development and the influence of external stakeholders in local curriculum development.