This study explored the conceptions of science teaching held by Resident Scientists who were providing content and pedagogical support to teachers in schools through the National Science Foundation (NSF) GK-12 project in USA. Their conceptions of teaching were compared with those held by teachers and the appropriate conceptions of science teaching reported in previous studies. A sample comprised nine Resident scientists from three science disciplines: biology, chemistry and physics. All the Resident Scientists were training to be scientists and not to be certified as teachers. Data was collected through a questionnaire and semi-structured interview. Data were analyzed by first coding the responses to identify recurring themes and categories. Five conceptions of science teaching emerged: Facilitative process, Conceptual and skill development, Ability and attitude development, Dynamic interactive process, and Content knowledge delivery process. Most conceptions of science teaching held by the Resident Scientists were similar to those held by teachers reported in previous studies. They also had elements for appropriate conceptions of science teaching. However, some Resident Scientists’ views on teaching supported the knowledge transmission instructional mode. The findings have implications for teacher education, science teaching and learning, and the National Science Foundation (NSF) GK-12 program.