TY - THES M1 - tesis N2 - The research aims to investigate (1) the accuracy level of the inflectional morphemes, and (2) the factors contributing to the inaccurate inflectional morphemes used by the third semester EFL students of Yogyakarta State University. This study is a descriptive qualitative study. The subject is 46 EFL students? writings. There are two instruments in this research. They are writing tasks and research questionnaire. The data were collected through the writing tasks and questionnaire. The data were analyzed using the descriptive statistical analysis. The criterion level on the accuracy of inflectional morphemes is 80 % based on the definition by Brown (1973) used in L1 acquisition research (Ellis, 1994). The results of the research reveal that there are three types of inflectional morphemes in the accuracy levels. They are Inflection ?ing(Present Progressive) with 91.21 % accuracy, Inflection ?est(Superlative Adjective)with 85.71 % accuracy, and Inflection -ed (Past Tense)with 83.13 % percent accuracy. The other five inflectional morphemes that do not attain accuracy level are Inflection -s, -es, -ies (Plural Noun) with 76.63 %, Inflection ?s?, -s? (Possessives) with 67.96 %, Inflection -s, -es, -ies (Third Person Singular Present Tense) with 72.81 %, Inflection ?ed and ?en (Past Participle) with 62.50 %, and Inflection ? erS(Comparative) with 55.56 %. Thus, the two major sources of error are intralingual or first language interference and intralingual which covers overgeneralization, ignorance of rule restriction, incomplete application of rules, and false concept hypothesis. UR - http://eprints.uny.ac.id/70374/ Y1 - 2020/02/28/ KW - accuracy level KW - inflectional morphemes KW - interlingual factor KW - intralingual factor. ID - UNY70374 AV - public TI - The Accuracy Level of Inflectional Morphemes Used by the Third Semester EFL Students of Yogyakarta State University. PB - Program Pascasarjana A1 - Tewarat, Sipri Hanus A1 - Sugirin, Sugirin ER -