Problem. The integration of computer science (CS) into K-5 classrooms alongside subjects like math, science, and literacy is growing but requires addressing intrinsic barriers related to teachers’ beliefs, values, and dispositions, which remain underexplored. Research Question. Our research question for this study was What are intrinsic barriers to supporting the integration of computer science in the elementary grade level subject areas? Method. We conducted a mixed methods study, including a survey ( \(n=160\) ), a set of focus groups ( \(n=23\) ), and a set of interviews with experts ( \(n=9\) ) with K-12 education decision makers and curriculum designers. We synthesized the results, establishing categories within intrinsic barriers. Findings. We found four categories of intrinsic barriers: limited teacher content knowledge, pedagogical content knowledge, and teacher beliefs about CS, as well as varied teacher perspectives on CS integration. Some of these also related to relearning or learning supporting educational technologies, limited buy-in, and how to meet the learning needs of all of the students in their classrooms. Implications. This study elucidates intrinsic barriers that K-5 classroom teachers face, particularly in the context of previous related research. We found that all of the intrinsic barriers uncovered have been encountered in other integration research. This provides the community with an opportunity to learn how barriers in similar fields were mitigated so that the intrinsic barriers in K-5 CS integration can potentially employ similar strategies.