Transfer of learning involves applying what has been learned to new tasks or situations in a flexible manner. Studies have long focused on the transfer capacities of adults, based on paradigms that were initially associationist, then behaviorist and cognitivist. This chapter discusses cognitive flexibility as a third avenue that may help explain the transfer difficulties observed in children. Demonstration of the action by an adult is the condition that leads to the highest transfer performance, due to a significant overlap between the two actions actually performed, one by the experimenter and the other by the child. Cognitive strategies are procedures or sets of procedures implemented to achieve higher level goals. The chapter shows that the transfer of learning may also benefit from a form of attentional flexibility. The links between transfer and flexibility will need to be investigated by incorporating metacognition.