Does age play a role in language acquisition?

Yes, age plays a role—but probably not in the simple sense that children always learn faster.

Older children and adults often make faster progress at the beginning. They already understand many concepts, can use conscious study, and can combine language acquisition with deliberate learning methods. Young children, however, are more likely to reach native-like ability over the long term, especially in pronunciation.

The broad pattern is:

• Older learners often progress faster initially.
• Younger learners are more likely to reach native-like ability eventually.

What does the research show?

Krashen, Long, and Scarcella’s review found that older learners generally made faster initial progress, while younger starters tended to perform better after years of exposure.¹

Other findings make the picture less straightforward:

• Under controlled input conditions, older children and adults were better than younger children at imitating unfamiliar foreign sounds.²
• In a later study, older learners again tended to make faster initial progress, although younger learners caught up after longer exposure.³
• A large study suggested that the capacity to learn English grammar remains high until around age 17 and then declines. A later reanalysis argued that the same data may fit a gradual decline better than a sharp critical-period boundary.⁴

Why are children and adults difficult to compare?

Children and adults usually encounter very different learning conditions.

Children often receive enormous amounts of simple, repetitive, and highly contextual language. Adults point at objects, use gestures, repeat themselves, and adjust what they say. Children also spend substantial time immersed in the language and may need it to interact with the people around them.

Adults rarely receive the same input. Native speakers may simplify less for them, beginner material may not hold their attention, exposure may be limited to a few hours per week, and they can often fall back on their first language.

This makes it difficult to separate age itself from differences in the quantity and quality of input, immersion, motivation, social need, and opportunities to use the language.

What can we conclude?

The evidence does not show that adults would outperform children in the long run if their conditions were identical. It does show that adults retain substantial language-learning abilities and can progress quickly, particularly at the beginning.

An important question remains open: If adults received as much comprehensible, engaging, and socially necessary input as children, how much of the observed age difference would remain?