ETP (English through Persian) is a newly-proposed method of second language teaching based on Vygotsky’s sociocultural model of EFL teaching in the context of Iran which has focused on localization as well as the influential role of L1 in L2 learning. Rahimi and Izadpanah (2015), proposers of ETP method, developed ETP course books which were the first localized English book series for Persian speakers. The present study attempted to investigate both ETP method and the related books in order to distinguish whether it is appropriate enough to help Iranian EFL learners acquire English competence. To this end, four sessions of ETP classes, from different levels, were observed. In addition, four sessions were dedicated to semi-structured interview with a sample of three teachers as well as five learners. Finally, two books, ETP 1 & 2, were evaluated based on an eclectic checklist proposed by Yusuf Demir and Abdullah Ertaş (2014). The findings of the study demonstrated a paradox between the interviewees’ positive feedback and the results of the two textbooks’ evaluation. Although ETP, as a method, was supported by both students and teachers, textbook evaluations revealed that translation could only be helpful in some situations like clarifying complex grammar points and explaining new words. Moreover, ETP books needed more consideration and revision.