Whether teachers' conceptions of NOS are reflected in their instructional planning and classroom practice remains an important research question. Consequently, this study investigated teachers' NOS views and their relationship to their classroom practice and delineated the factors that facilitate or impede this relationship. To achieve this, seven high school biology teachers with teaching credentials were selected to participate in this study. These teachers filled out an open-ended questionnaire entitled Views of the Nature of Science Questionnaire, participated in semi-structured interviews, were videotaped, and their lesson plans were collected. Results showed that most teachers do not possess appropriate NOS views, lesson plans lacked any planning for teaching NOS, and teachers' practices lacked any explicit reference to the aspects of NOS.