This dissertation investigated the role of English in Iranians learners’ understanding of culture and intercultural awareness, from the perspective of both the formal teaching of English and of learners’ informal experiences of learning and using English. The theoretical framework drew on research on English as a global lingua franca in an increasingly globalized world and research on the role of culture in language teaching and learning. Methodologically, the study was qualitative in nature and content analysis and thematic analysis were applied in analyzing the data. Two data sets, comprising seven global English textbooks and in-depth interviews with eight – young adult – learners were analyzed. The results were reported in three substudies.