Mathematics, science, and technology are three disciplines that are highly discussed in national and international circles, especially as regards their importance to the success of young people after they leave school. With that, the purpose of the study is to examine the integration of technology into mathematics and science instruction in secondary education in Taiwan in order to make comparisons to the integration of technology into mathematics and science instruction in secondary education in the United States. The design of the study is qualitative, and comes from two theoretical traditions, which had their roots in anthropology (ethnography) and the social sciences (reality testing). Results and conclusions show that four factors are essential determinants of teachers regularly using technology in their mathematics and science classrooms. These factors are (1) whether or not the current technology is available, (2) the availability of professional development and training, (3) the interest level of the teachers, and (4) the most important factor affecting technology use is the involvement of the school principals.