Many disciplines have used concept inventories (CI) to better understand the alternative ideas held by students. Administering a CI at both the beginning and the end of the semester can yield much information. For example, a comparison of both pre- and post-test responses can help determine if specific gains in student learning were met. In this paper, we describe the development of a concept inventory over four academic years for the one-semester general, organic, and biochemistry (GOB) course required for nursing students. Questions were designed around course topics and to identify common misconceptions, which were gathered from the literature, student interviews, and content experts. The instrument was refined over several iterations to ensure that all questions were appropriate and understandable while providing useful information. The final version demonstrated appropriate gains in the comparison of pre- and post-test results for an active learning classroom and results are discussed. In addition, item quality was ascertained via the discrimination and difficulty values, and Cronbach's alpha coefficient was computed for the entire test as a measure of its reliability.