Efficient language use involves the capacity to flexibly adjust to varied pronunciations of words. Although children can contend with some accent variability before their second birthday, it is currently unclear when and how this ability reaches its mature state. In a series of five experiments, we examine the developmental trajectory of toddlers' comprehension of unfamiliar regional accents. Experiments 1 and 2 reveal that Canadian-English-learning 25-month-olds outperform their 20-month-old peers on the recognition of Australian-accented words and that this effect is likely driven by 25-month-olds' larger vocabulary size. Experiments 3 to 5 subsequently show that 25-month-olds' recognition of familiar words holds regardless of prior exposure to the speaker or accent. Taken together, these findings suggest that children's ability to cope with accent variation improves substantially as their vocabulary expands in the second year of life and once it does, children recognize accented words on the fly, even without experience with the accent.