This research was an attempt to investigate the relationship among teacher–student interaction (TSIn), student’s socio-economic status (SES), willingness to communicate (WTC), anti-ought to self (AO), and language achievement (LA). To fulfill the research objectives, a quantitative approach was employed. The participants of the current study were 1076 undergraduate students (male and female) randomly selected from among students of different majors in Isfahan University of Technology, Isfahan University of Medical Sciences, and University of Isfahan. To collect the data, the participants were asked to complete a questionnaire which was a combination of the Questionnaire on Teacher Interaction (QTI), WTC questionnaire (MacIntyre, Baker, Clement, Conord, 2001), and Anti-Ought to self questionnaire (Liu Thompson, 2018) as well as students’ socio-economic status information. Also a Language Achievement Test was used to assess the participants’ success or failure in language achievement. For data analysis, SEM and AMOS statistical techniques were used. Utilizing SEM, two multiple group structural equation models, once with considering students’ test scores and once without taking into consideration test scores, were conducted. Then goodness of fit indices was checked in six steps by applying Maximum Likelihood (ML) and Bootstrap methods. In general, the results of the study are as follows: TSIn was directly and indirectly related to WTC; the relationship between TSIn and AO was accepted; there was a significant relationship between AO and WTC. With regards to the relationships between SES and other variables, only the direct and positive relationship between SES and WTC as well as SES and LA were confirmed. The findings pertaining to the relations of SES, TSIn, WTC and AO with LA indicated that all variables, except TSIn, were related to the students’ success in LA. However, the relationship between AO and LA was negative, that is, if AO increases, LA will decreased, which was contrary to the results of the previous studies. At the end, the suggestions for the future research studies were presented and some pedagogical implications were discussed. Keywords: Teacher-student interaction; Willingness to communicate; Anti-ought to self; Socio-economic status; Language achievement
