Children are born without any linguistic knowledge, so all language learning is a result of the environment. Children react to language stimuli with responses; if their responses are correct, they are reinforced and then become habitual. Skinner: verbal behavior controlled by its consequences - rewarded consequences result in maintenance and increase/frequency of the behavior. Behavior is weakened and eventually extinguished when it evokes either a punishment or is completely ignored.
Behaviorist theory fails to account for the fact that children construct completely new sentences that are not the result of imitating models