The purpose of this study was to explore the perspectives of general and special education teachers regarding the barriers to the successful implementation of co-teaching in inclusive classrooms at an elementary school in the state of Colorado. The research employed observations and semi-structured interviews with eight co-teachers. By employing thematic analysis, the results found the following factors are considered significant by general and special education elementary school teachers: (1) lack of shared vision of co-teaching; (2) lack of co-teaching planning time; (3) lack of effective instructional supervision and establishment of clear expectations; and (4) insufficient opportunities for professional development.