This paper presents the development and revision of a dual-response instrument entitled, “Student Understanding of Science and Scientific Inquiry (SUSSI).” Built on the most recent science education reform documents and existing literature on the nature of science, SUSSI blends Likert-type items and related open-ended questions to assess students’ views on the nature of scientific knowledge development in terms of six aspects: observations and inferences, tentativeness, scientific theories and laws, social and cultural embeddedness, creativity and imagination, and scientific methods. This combined quantitative and qualitative approach is a form of triangulation, which can increase confidence in the findings and help us obtain a fuller understanding of the respondents’ views on the nature of scientific knowledge.