During the decades following Piaget's work, it has been believed that correct judgments of durations require sophisticated reasoning abilities that emerge at about 8 years of age. However, a number of researchers have demonstrated that young children's poor judgments in classical Piagetian tasks are not due to their inability to judge time correctly, but rather to their limited attentional capacities. Recent research has therefore concentrated on further investigating the development of abilities to discriminate durations in young children on the basis of the temporal tasks initially used with animals within the framework of the internal clock theories. This manuscript reviews and discusses the results of these studies.