This paper examines three in-service science teachers' use of argument-driven inquiry (ADI) instructional model in an urban school district. We explore the basis for teachers' adaptation of the ADI model. The data were collected through teacher interviews and classroom observations from three science teachers. Data analysis indicated that three teachers utilised the ADI model in different ways; their implementation is aligned with the intentions of the ADI model or science teachers adapted or omitted the phases of the ADI. The teachers' practices were influenced by their personal beliefs including beliefs about teaching and learning science and students' ability and contextual factors such as district and standards, curriculum, and testing. The study provides suggestions about science teacher education and the development of new curriculum materials.