The cost of textbooks is a financial burden on many college students. Fortunately the advent of open educational resources (OER) has allowed for the development of textbooks and other materials at significantly reduced costs to students. Many faculty are using OER to develop customized textbooks for their students, usually published digitally online. These faculty desire high fidelity feedback from their students to help them improve their texts. However, there is no general model of what digital textbook quality means to college students. Such a model would allow for the development of a measure of digital textbook quality that could provide highly valid and reliable student feedback for faculty to use in improving their open textbooks. This study describes a mixed-methods approach for developing a model of digital textbook quality from the college student perspective. An instrument for measuring the components of this model is also described. This dissertation can be freely accessed and downloaded from http://etd.byu.edu/ or from http://tjbliss.org/dissertation.