This study aims to enhance our knowledge of the associations between the quality of the language-learning environment in toddler childcare groups and children's vocabulary development from age 3 to age 5. Participants were 1,131 children (48% girls; age at T1 assessment: M = 35.5 months, SD = 2.7; age at T2 assessment: M = 60.3 months, SD = 1.4) from 206 toddler groups from 93 centres. Multilevel analysis showed that the quality of the language-learning environment experienced in toddler groups was associated with verbal ability at age 5 when controlling for verbal ability at age 3 and the quality experienced in kindergarten groups at age 5. These results indicate that toddler language-learning environments characterised by responsive staff, extended talk, and facilitating conversations promote vocabulary development. The effect, albeit small in magnitude, points to the importance of a rich and varied language-learning environment during the early years. Implications for policy and practice are discussed.