This study was undertaken to evaluate Iranian ELT English textbooks (Senior High school and Pre-University) in the light of three learning theories i.e., behaviourism, cognitivism, and constructivism. Each of these learning theories embedding an array of instructional strategies and techniques acted as evaluation checklist. That is, Iranian ELT English textbooks were evaluated in terms of instructional strategies and techniques cited in the related literature for each learning theory. The analysis of data in this descriptive study through frequency count and relative frequency revealed that the major principle of organization in Senior High school is the learning theory of behaviourism. Although Constructivism was observed to be the prominent learning theory in Pre-University English textbooks, combination of other learning theories were indicated. It was also indicated that cognitivism was rated as the second most important learning theory across all educational level. Analysis of the data through Chi-Square showed that reflection of learning theories in Iranian ELT textbooks is not by chance and the differences are significant with behaviourism on the one side, cognitivism in between and constructivism on the other side of continuum.