The work presented in this thesis focuses on teaching ethics in primary science classrooms. Such teaching is important because it engages students not only in the human aspects of science, but also in science more generally, leading to enhanced scientific literacy and ultimately contributing to responsible citizenship. Teaching ethics in science also presents opportunities for developing students’ argumentation, critical thinking and decision-making skills, and helps students become more ethically aware, knowledgeable and discerning in science. Ethics in science has a prominent role in the New Zealand Curriculum within the ‘nature of science’ strand in the science learning area. However, there is a paucity of research demonstrating how this might be implemented with primary-age students. This work determines firstly whether primary students can engage in ethical discussions in science. Secondly, it focuses on the question of support needed for primary teachers and whether it is helpful for teachers to use a subject-specific planner for teaching ethics in science. The research adopted a sociocultural view of learning, in which learning is understood to be of a social and collaborative nature. The research involved two teacher development sessions, where three teachers were introduced to ethics concepts, examples on how they could be taught in a science context, and an ethics-in-science planner. Teachers subsequently developed and implemented an ethics in science programme using the ethics-in-science planner in their classrooms. The data for this research were collected from three teachers within the same school. Document analysis, interviews and classroom observation provided data triangulation. The findings suggest that young students can engage in ethical discussions in science – and do so, enthusiastically. They also confirm that primary teachers need support to teach ethics in science. For example, all three teachers reported the development sessions were necessary to help them understand ethics concepts and to give them ideas and strategies for teaching ethics in science. This is supported by research demonstrating that intervention in the form of teacher development and planning is vital for teachers to develop pedagogical content knowledge in a new area. In particular, teachers reported that the ethics-in-science planner helped them consider the classroom interactions on which they wanted to focus the outcomes, demonstrating that ethics in science can be meaningfully taught in the primary classroom. This raises the issue of teacher development and how this would be funded and implemented for the purpose of developing the pedagogical content knowledge of primary teachers for the teaching of ethics in science.