Verbs serve as the architectural centerpiece of sentences, making verb learning pivotal for language acquisition. Verb learning requires both the formation of a verb-action mapping and the abstraction of relations between an object and its action. Two competing positions have been proposed to explain the process of verb learning: (a) seeing a highly variable range of exemplars allows children to detect and abstract the commonalities across actions--the action invariants; and (b) seeing a less variable range of exemplars enables children to focus on and extract the action invariants. Using manner--a major component of verb meaning in English--as a test case, this study addressed this debate by examining the influence of manner variability on the ability to fast-map new verbs and extend them to novel exemplars in 2-, 3-, and 4-year-old English-speaking children. Results contribute to this debate by showing that high manner variability hindered fast-mapping but facilitated extension to manner variations in the 2- and 3-year-olds. Thus, high exemplar variability may affect verb fast-mapping and extension differently. Furthermore, manner variability did not affect 4-year-olds' (or adults') fast-mapping or extension, suggesting that the influence of exemplar variability on verb learning attenuates with age. Finally, manner variability did not affect agent or object extension, revealing a component-specific effect of exemplar variability on verb extension.