Success in second language learning is often related to the concept of 'motivation'. Motivation is the most used concept for explaining the failure or success of a language learner. This paper collected and reviewed the literature of motivation in second language acquisition (SLA) form prominent journals in the field. The role of motivation as one of the most important constructs of individual differences (IDs) in foreign language learning and their relationships with second/foreign language learning are investigated. The wider concluding argument of this paper is that motivation and its constructs are context dependent and, therefore, any language learning situation has its own unique motivational model.