Analyzed effects of modeling and contingent praise on infant imitation of three responses: motor-with-toy, motor-without-toy, or vocal. Found a systematic increase in the percentages of training and probe models matched by the three 12- to 14-month-olds following introduction of model-and-praise treatment conditions. Nonmatching responses did not systematically increase. Thus, imitation generalized within response class, but not across response classes. (Author/KB)