Language is critical to the development of young children; it is essential for learning and communicating with others. Children learn most effectively by being involved in rich hands-on experiences and activities fostered through play, and adults need to join in this play by talking and listening to them. Several theories have been formulated about how young children acquire language. Some argue that the environment is an important factor, while others argue that language is innate and that the environment plays a minor role in the formation of knowledge. The first group is called the “behaviorist school”. For them, children come into the world with a clean slate and are then shaped by the environment and slowly conditioned through positive or negative reinforcement. They learn a language step by step through imitation, repetition, memorization, controlled practice, and reinforcement. They receive reinforcement from their parents after speaking correctly (operant conditioning) and he will want to continue speaking to get the same positive reaction. Therefore language acquisition is a process of habit formation. BF Skinner is the best-known behaviorist who hypothesized that children are conditioned by their environment to respond to certain stimuli with language. And if a particular response is reinforced, it becomes habitual or conditioned. According to behaviorists, the role of the environment is fundamental and vital to the learning process. The environment is the active agent while the student is the passive agent. The environment produces the necessary linguistic input for the learner and it is up to the environment to provide positive and negative reinforcement for the learner. Furthermore, children are not born with innate abilities; t...... half of the paper ...... it's about (degenerate) language, the fact that at such a young and cognitively limited age children are still able to acquire language quite quickly indicates that they were born with this ability (the opposite view of behaviorists who argued that the environment was the sole cause of language development). Children produce grammar without having learned any grammatical rules. For example, in WH questions children do not produce questions by moving the auxiliary, but they correctly invert the auxiliary of the main clause instead of the first auxiliary. To conclude, although behaviorism may not tell us much about how a first language is acquired, it can point to successful strategies for acquiring a foreign language as one gets older. Furthermore, despite the criticism, the environment still plays an important role in language acquisition.