Students with disabilities have limited opportunities to become problem solvers due to the deficit‐thinking mindset of their teachers. Thus, technology could facilitate the development of problem‐solving skills for these students, which requires an understanding of student computer attitudes in science, technology, engineering, and mathematics (STEM) problem‐solving. However, there is limited research about computer attitudes in problem‐solving for students with disabilities. To address this challenge, this study first developed a questionnaire on computer attitudes in problem‐solving in STEM (Colorado assessment of problem‐solving [CAPS]‐STEM) and validated this instrument for the population of elementary school students with disabilities (N = 199). The questionnaire was then used in a sequential explanatory mixed methods study to examine factors affecting CAPS‐STEM for students with disabilities in two inclusive classrooms. Results of the study indicate significant positive correlations among students' self‐perceived confidence, knowledge, and competence in using computers for STEM problem‐solving. These attitudes were mostly affected by the nature of the assigned projects, existing school support for teachers, available technology resources, and teachers’ mindsets about the abilities of students with disabilities.