Background: Scientific models have important roles in science and science education. For scientists, they provide a means for generating new knowledge or function as an accessible summary of scientific studies. In science education, on the other hand, they are accessible representations of abstract concepts, and are also organizational frameworks to teach and learn inaccessible facts. As being indispensable parts of learning and doing science, use of scientific models in science classes should be reinforced. At this point, uncovering pre-service science teachers' (PSTs) understandings of scientific models are of great importance since they will design and conduct teaching situations for their students. Purpose: The study aimed to provide an answer to the research question: What understandings do PSTs possess about scientific models? Sample: The sample of the study consisted of 14 PSTs enrolled in an Elementary Science Education program in a public university in Ankara, Turkey. Design and methods: Data were collected by using an open-item instrument and semi-structured interviews, and were analyzed by using qualitative data analysis methods. Results: Findings showed that PSTs held "fragmented" views of models by having informed views in some aspects while having naïve views on others. That is, although they displayed a "constructivist orientation" by acknowledging the presence of multiple models for the same phenomenon depending on scientists' perspectives or creativity involved in the production of scientific knowledge, PSTs also expressed "logical positivist" views by believing that models should be close to the real phenomena that they represent. Findings further revealed that PSTs generally conceptualized models' "materialistic uses," yet they did not think much about their theoretical and conceptual uses. It was observed that roles like reifying and visualizing were overestimated and models were dominantly characterized as three-dimensional representations. Conclusions: It is clear that PSTs, having difficulties in grasping the concept of models, would possibly have problems in planning their lessons effectively and would not develop accurate concepts in their students. These findings apparently support the need for appropriate pedagogic training of PSTs to scientifically reflect on and professionally make use of models in science classes.