The influence of a model's age on young children's behaviour has been a subject of considerable debate among developmental theorists. Despite the recent surge of interest, controversy remains about the nature of peer influence in early life. This article reviews studies that investigated the influence of a model's age on young children's behaviour in the first 5 years of life, and presents an account of seemingly mixed results. We propose that children imitate familiar behaviour for social reasons, such as in order to identify with the model or to communicate likeness. Since age is an important indicator of the degree of being alike, we propose that children are more likely to imitate familiar behaviour from peers. In contrast, we propose that children primarily imitate novel behaviour for learning reasons. Since adults are perceived as being more competent than children, children are more likely to learn from adults. We further suggest that increased peer experience leads children to evaluate peers as valuable resources for learning novel behaviour in domains in which peers are knowledgeable. Copyright © 2013 John Wiley & Sons, Ltd.