One general perspective on why children over-imitate is that they are learning about the normatively correct way of doing things. If correct, then characteristics of the demonstrator should be relevant. Accordingly, the current study aimed to investigate how the reliability of an adult model influences children’s selectivity of what to imitate in an over-imitation situation (i.e., when some of the actions are causally irrelevant). Seventy-eight preschoolers between 3 and 6 years of age participated at school or in the lab on four tasks. A canonical trust paradigm was used to manipulate model reliability in terms of past accuracy. Children then watched either the reliable or unreliable model open a transparent box using the same relevant and irrelevant actions. In addition, children completed a standard ToM battery. Results indicated that children were more likely to over-imitate from a demonstration given by the reliable versus unreliable model. Children’s ToM abilities were not related to their over-imitation behavior but showed some relations to their trust performance. Overall, the results provide support for a social situational approach to over-imitation that fits most closely with the norm learning perspective.