This book uses the paradigm of the child as a problem solver to examine various theories of cognitive development. * Provides balanced coverage of a broad range of contemporary theories. * Focuses on collaborative tasks which are carried out with other children or adults. * Asks whether social interaction is the key to improvement in problem solving skills or whether it is the skills & abilities that the child brings to the task that are paramount. * Draws on a wide range of research including the authors own research into dyadic problem solving.