Research investigating faculty and instructors’ perception of teaching in discipline oriented fields such as biology, chemistry and physics suggest that faculty hold diverse <br>conceptions about teaching and learning. This study extended this work to a discipline at the interface between traditional physical science and life science fields, upper-level biochemistry courses. It also compared instructors’ perception, beliefs and actions when teaching biochemistry at research institutions with courses taught at primarily <br>undergraduate institutions (PUI’s). In a recently completed review of discipline-based educational research (DBER) in <br>biochemistry, I noted the absence of research regarding the relationship between faculty beliefs and classroom practices in biochemistry and noted that different levels, associated <br>with teaching and learning experiences, have not been studied in the context of the undergraduate chemistry curriculum. As a scientific field, biochemistry bridges chemistry and biology, which each have a consensus regarding the major concepts or ideas that should <br>be taught within their disciplines. However, biochemistry, despite its increased relevance in recent years, has achieved hardly any consensus among those who teach this content material on what should be taught or how instructors should teach it. Biochemistry is also a rapidly growing field with increased relevance that is being taught as a unique discipline in more and more institutions. Another unique feature that distinguishes biochemistry from other scientific fields is that it is inherently interdisciplinary and taught in different departments, often for a versatile population of various majors and minors. Further research suggests that we overgeneralize conclusions on factors influencing teaching practices within classrooms, which could possible prevent the advancement of teaching methodologies used by instructors. To explore this research interest, classroom <br>observations and semi-structured interviews were used. <br>Within the scope of this study, I identified two main ways biochemistry instructors thought about their teaching of biochemistry: theory versus practice-oriented. The more <br>theory-driven instructors reflected on their beliefs and perceptions, the more traditional their teaching practices were executed – the contrary held true for instructors with a more practical conception of the teaching of biochemistry. Overall, I was able to portray a multitude of ways in which biochemistry is currently being taught at different institutions, <br>identifying differences and communalities they shared. As well as the unique challenges instructors faced when implementing evidence-based teaching methodologies in their classrooms were identified and categorized. My research should improve the understanding of factors, barriers, and possible opportunities that various scientific <br>disciplines face to inform the development of professional programs that can encourage the use and implementation of evidence-based instructional practices.