The study of the complex impact of the cognitive and psychological factors' interplay in learning process has for long obsessed educational researchers. In an attempt to partially address the issue, the present study investigates the direct and indirect interrelationship among Iranian EFL learners' basic psychological needs satisfaction, goal-orientation, willingness to communicate, learning strategy use, self-efficacy and second language achievement through a path analytic research design. To this end, 506 Iranian undergraduate English students took the related questionnaires and based on the collected data, a hypothesized model of interrelationship among variables was tested using AMOS statistical package. According to the final path analytic tested model, L2 achievement was predicted by goal orientation, self-efficacy, and learning strategy use. Moreover, while basic psychological needs satisfaction did not directly predict L2 achievement, it was indirectly associated with L2 achievement through goal orientation. The findings imply that the teachers need to first identify the most relevant individual sources of performance variation in their context and next design procedures to maximally cope with inhibitive psychological or cognitive factors which associate with their learners' rate and route of learning. Moreover, language learners need to be more oriented towards setting their future goals, believing in their capabilities, and use more learning strategies.
Keywords: Cognitive individual differences; Iran; L2 achievement; Psychological individual differences.