Biochemistry is a challenging subject because student learning depends on the application of previously learned concepts from general chemistry and biology to new, biological contexts. This article describes the development of a multiple-choice instrument intended to measure five concepts from general chemistry and three from biology that are considered prerequisite for biochemistry learning. This instrument is specifically designed with a factor structure that includes three multiple-choice items for each of the eight concepts and the most common incorrect ideas that students could have as distractors. It can be used as a pretest to identify students' incorrect ideas about those concepts and to determine if instruction helps students overcome those incorrect ideas when used as a posttest. Results from a confirmatory factor analysis support a very good fit for an eight-factor solution. This manuscript represents a report on the current state of instrument development. We seek to share our methods and instrument design principles with the broader community. (Contains 7 tables and 1 figure.)