Research on very young children's cognitive development differs greatly from research on cognitive development in older children. The differences include the questions asked, the methods used, the measure employed to provide evidence, and the level of detail at which children's knowledge is represented. The approaches have been so different that it creates the impression that infants' and toddlers' thinking differs qualitatively from that of pre-schoolers and other children. This monograph presents a detailed study of toddlers' problem solving and learning, using microgenetic methods and analyses that have been used with older children. The conclusion is that the gap can be bridged and that theories, methods, measures, and representations of knowledge typically used with older children can improve our understanding of toddlers' problem solving and learning as well.