This study addresses the acquisition of the morphological markers in Persian learners of English as a foreign language. To this end, the accuracy order of nine morphemes including plural –s, progressive –ing, copula be, auxiliary be, irregular past tense, regular past tense –ed, third person –s, possessive -ʼs and indefinite articles was studied in 60 teenage Persian EFL learners. Placement and proficiency tests and a demographic questionnaire were employed to collect the data. The total production of 2160 morphemes was manually checked, classified, and counted to rank their acquisition order. The learners’ accuracy order was ranked in a decreased order from 1 to 9 as follows: regular past tense, auxiliary be, copula be, present progressive tense, indefinite articles, plural –s, possessive -ʼs, irregular past tense and third-person singular –s. The Spearman correlation showed that Persian students’ accuracy order had a moderate and weak relationship with the accuracy order of ESL and EFL learners, respectively. This finding proves that Persian EFL learners do not learn English grammatical morphemes in a natural order. Moreover, the universal grammar does not remain fully in these learners. The minor role of UG in EFL acquisition also indicates the important role of transfer in foreign language learning.
