The document discusses research on the effects of age on second language acquisition. Studies have found that learners who begin acquiring a second language at a younger age tend to achieve higher levels of proficiency, especially in terms of pronunciation and grammar. Younger learners in naturalistic learning environments often reach near-native levels of ability, whereas older learners show less overall control of the target language. While the process of acquisition appears similar for children and adults, age may have a more significant effect on pronunciation development than grammar.