The goal of this research was to study the relationship among willingness to communicate (WTC), international posture (IP), and competitiveness (COM), and to see if socio-economic status (SES), as a sociological factor, has any effect on these factors and their relations. As another aim of the present study, the relationship among these factors and language learners’ achievement was investigated as well. To this end, a quantitative approach was utilized to study university students' responses to a questionnaire. The participants of the study were 1084 university students selected randomly from different majors studying at Isfahan University of Technology, Isfahan University of medical Sciences and University of Isfahan. To collect data, a questionnaire was developed measuring SES, IP, COM, and WTC of participants. In order to analyze the data, inferential statistics were reported and utilizing AMOS, Structural Equation Modelling was conducted. Two models were conducted the first model didn’t consider participants test score and Language Achievement (LA) but the second one considered the test scores. According to the results, SES was approved to have impact on WTC, IP, and COM, and on the relation which exists among them. IP had direct impact on COM and WTC, but the impact of COM on WTC was rejected. According to the second model of the study, LA was affected by learners’ SES and their level of WTC, but learners’ COM and IP had no direct impact on their LA. Keywords: socioeconomic status, willingness to communicate, international posture,, competitiveness, language achievement