This chapter is based on three propositions: (1) learning is central to child development, (2) microgenetic analyses yield unique information about learning, and (3) the information yielded by microgenetic analysis is helping to create a vibrant new field of children's learning. In addition to providing arguments and evidence for these propositions, the chapter describes conclusions from microgenetic studies regarding the path, rate, breadth, variability, and sources of children's learning. Among the main conclusions are that: within-child variability is substantial at all ages from infancy to older adulthood, initial within-child variability tends to be positively related to subsequent learning, learning tends to progress through a regular sequence of knowledge states that parallel untutored development, the path of learning is usually similar for learners of different ages and different intellectual levels, new approaches are generated following success as well as failure of existing approaches, and requests to explain observations often promote learning above and beyond the effects of feedback and practice.