The goal of this thesis was to investigate and enhance our understanding of what occurs while pre-service mathematics teachers engage in a mathematical modeling unit that is broadly based upon mathematical modeling as defined by the Common Core State Standards for Mathematics (National Governors Association Center for Best Practices & Council of Chief State School Officers [NGA & CCSSO], 2010). Qualitative data was collected during an instructional unit on mathematical modeling in a methods course for secondary pre-service teachers. Three different vantage points were taken, resulting in two research based articles and one practitioner article. The first article examines the mathematical modeling process used by pre-service teachers to solve mathematical modeling tasks. Results in this paper show that the cycle described and illustrated in the Common Core State Standards for Mathematics (CCSSM) do not represent the work done by these students. An alternate theory of the mathematical modeling process is suggested that recognizes free movement between the objects and actions of mathematical modeling. The second article explores how students engaged in mathematical habits of mind while engaged in solving a realistic mathematical modeling task. The results of the study show that students engage in the habits of mind to solve the task. Additionally, the results suggest that a more thorough and interconnected use of the habits of mind create a more general solution to these types of tasks. The final article gives a detailed account of the implementation of a mathematical modeling unit in a capstone mathematics education course for secondary mathematics teachers and reviews the results of this implementation. Findings suggest that the unit was successful in helping students develop appropriate conceptions of mathematical modeling. Together these articles show the complexity of mathematical modeling in the classroom and show the benefits of investigating mathematical modeling from multiple perspectives. Implications for the mathematics classroom are offered. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]