My thesis work is focused on conceptual and epistemic learning and characterizing the environments in which this learning takes place. Earlier studies conducted by the Stowe group explored how instructional practices, instructional emphasis, and assessment emphasis relate to student outcomes in general and organic chemistry courses. Student outcomes were measured using short homework assignments that asked students to model and explain a chemical phenomenon. These studies demonstrated that what is taught and assessed is at least as important as how classes are taught. However, we did not have control over the learning environments in either of these studies. To more carefully investigate the influence of instructional practices on student outcomes, we carried out a study in the context of organic chemistry learning environments we controlled. All course resources were shared, including assessments, and the main difference between learning environments was in the whole-class meetings. Half of the instructors in the study embedded explanation-focused clicker questions into their lecture slides, and therefore ~30% of class time was dedicated to active learning activities. The other half of the instructors lectured the entire time. The results of this study, along with implications for equity, will be discussed. For the second half of my thesis work, I shifted focus from what students drew/wrote to why they constructed knowledge in the ways they did. Specifically, we examined how students' experiences with assessment-related messages about valued ways of knowing and learning (i.e., epistemological messages) aggregated over the course of one semester of an organic chemistry lecture course. To do so, we interviewed nine students three times each throughout the semester. We observed how students' experiences with the course epistemological landscape solidified the way they approached the course and the goals they pursued. Assessments and answer keys were an overwhelmingly powerful source of messages about how students should construct knowledge and what "good" knowledge looks like. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]