Until recently, it was believed that to learn/teach another language, it is sufficient for a person to know the grammar of another language in detail, have a good command of its vocabulary, and be able to pronounce the words, phrases and sentences well. However, later it turned out not to be so easy since more important issues were discovered which made the learning/teaching of another language (SL/FL) more challenging than what it was previously thought. These issues are the social and the cultural aspects of L2/FL, the combination of which makes the sociocultural aspects of language learning and teaching. This means that, the circumstances under which we live, together with the symbols, symbolic tools, and signs we use to mediate and regulate our relationships with others, and with ourselves which make sociocultural theory are important issues for learning L2/FL. Later, the three generations of psycholinguistics are provided, the third generation of which is sociocultural theory together with the important notions of each generation. Finally, three educational implications of sociocultural theory are provided.