There exists a general consensus in the science education literature around the goal of enhancing learners' views of nature of science (NOS). An extensive body of research in the field has highlighted the effectiveness of explicit NOS instructional approaches in improving learners' NOS views. Emerging research has suggested that engaging learners in argumentation may aid in the development of their NOS views, although this claim lacks empirical support. This study assessed the influence of a science content course incorporating explicit NOS and argumentation instruction on five preservice primary teachers' views of NOS using multiple sources of data including questionnaires and surveys, interviews, audio- and video-taped class sessions, and written artifacts. Results indicated that the science content course was effective in enabling four of the five participants' views of NOS to be improved. A critical analysis of the effectiveness of the various course components led to the identification of three factors that mediated the development of participants' NOS views during the intervention: (a) contextual factors (context of argumentation, mode of argumentation), (b) task-specific factors (argumentation scaffolds, epistemological probes, consideration of alternative data and explanations), and (c) personal factors (perceived previous knowledge about NOS, appreciation of the importance and utility value of NOS, durability and persistence of pre-existing beliefs). The results of this study provide evidence to support the inclusion of explicit NOS and argumentation instruction as a context for learning about NOS, and promote consideration of this instructional approach in future studies which aim to enhance learners' views of NOS. (Contains 8 tables.)