this study investigates the strategies native english and persian speakers employ for expressing gratitude in different situations. the strategies of persian efl learners are also compared with english strategies in order to find the differences that may exist between these two languages. social status and size of imposition of the favor are social variables which are investigated in detail for three groups. unlike comprehensive studies on sas such as request and apology, the number of cross-cultural studies investigating expressions of gratitude is fairly limited and there are few studies investigating this speech act in persian. the participants of this study were 75 advanced students from the english department of isfahan university. the participants were both male and female, aging from 20 to 31 years old. 24 american college aged, native speakers also participated in this study. an open-ended dct were employed for studying participants responses and verbal reactions to different situations. the results of chi-square test suggested that persian and english speakers vary in their gratitude strategies. persian students’ sensitivity to social variables made them use inappropriate expressions and strategies in their english responses. it suggested that persian learners of english transfer some of their l1 pragmatic norms to l2 because they perceive these norms to be universal.