A study investigated Japanese children's acquisition of the syntactical subcategorization of action verbs. Aspects of caregiver language that provide children with information about the characteristics of an action verb are detailed, and the utterances of four Japanese toddlers are analyzed for their usage characteristics. Caregiver sentences are examined for evidence of how the use of action verbs in specialized contexts predicts syntactic classification of the verb. Developmental predictions for children's use of action verbs are tested, and it is concluded that the evidence supports this account of their acquisition. (MSE)