In line with the studies demonstrating the positive relationship between critical thinking ability, self-regulation and language proficiency, this study aimed to particularly examine the impact of the two subcomponents of critical thinking, i.e., inference-making and deduction, as well as one subcomponent of self-regulation, i.e., self-monitoring, on EFL students' overall language achievement, reading and writing achievements. To the best of researchers' knowledge, there is no documented study investigating the relationship between these constructs among EFL learners. To achieve the purpose of the study, 120 EFL university students were selected according to a convenience sampling from Hakim Sabzevari University, a city in the north-east of Iran. They were asked to complete the "Watson-Glaser's Critical Thinking Appraisal" and the "Self-Regulation Trait Questionnaire". They were also requested to report the grade point average of their previous term together with their reading and writing scores on these courses. The results showed that there is a significant relationship between EFL learners' inference-making, deduction, self-monitoring and their language achievement as well as their reading and writing ability. Subsequent data analyses demonstrated that among the variables, self-monitoring is the most powerful predictor of language achievement. In addition, the results revealed that the three mentioned variables can predict about 27 percent of language achievement. This study has some implications for educators and administrators to take full advantage of these associations by establishing guiding principles for enhancing EFL university students' self-monitoring, inference-making, and deduction.