Previous research indicates that infants generalize syntactic-like structures to novel exemplars in a way that has been characterized as abstract and algebraic (Marcus et al., 1999). Infants appear to learn and generalize from speech more successfully than from nonspeech stimuli (Marcus, Fernandes, & Johnson, 2007). In this series of experiments, we manipulated speech and nonspeech stimuli to identify the factors that facilitate or inhibit infants' learning and generalization. The results demonstrate that redundancy facilitates learning, even in nonlinguistic stimuli. In addition, the results indicate that learning from speech is inhibited when the speech is less redundant. These experiments suggest that speech and nonspeech stimuli are on a continuum of effectiveness, related to the ease with which infants can access and benefit from redundant information. The redundant information in the stimuli may be particularly related to the ease with which infants can detect repetition. (Contains 4 figures and 2 tables.)