Investigating the processes through which individuals acquire language is Language acquisition. In general, acquisition of language points to native language acquisition, which examines children’s acquisition of their first language, while second language acquisition concerns acquisition of extra languages in children and adults as well. The history of language learning theories can be considered as a great pendulum cycled from Skinnerian environmentalism to Piagetian constructivism to Chomskian innatism. Consequently, much of research in this field has been revolved around the debates about whether cognitive process and structure are constrained by innately predetermined mechanism or shaped by environmental input. Linguists Noam Chomsky and Eric Lenneberg, for half a century have argued for the hypothesis that children have inborn, language-specific capabilities that make possible and restrict language learning. Others, like Catherine Snow, Elizabeth Bates and Brian MacWhinney have hypothesized that language acquisition is the product of common cognitive capacities and the interface between children and their surrounding communities. William O'Grady suggests that multifaceted syntactic phenomena stem from an efficiency-driven, linear computational system. O'Grady refers to his work as" nativism without Universal Grammar. Nevertheless, these basic theories of language acquisition cannot be absolutely divorced from each other. The purpose of the present paper is reviewing some of the fundamental theories that describe how children acquire their native language. Therefore describing the strengths and weaknesses of Behaviorism, Mentalism, Rationalism, Empiricism, Emergentism, Chunking, Vygotsky’s Sociocultural Theory, Piaget’s theory of child language and thought, Statistical Language Learning, Relational Frame Theory and Activity theories are among the objectives of this study. In general these basic theories are very much complementary to each other, serving different types of learning and indicating diverse cases of language learning.