This article examines the prosociality of four-year-old girls and boys in childcare centres. More specifically, it aims to measure gender differences in prosociality among children, based on three sources and methods of evaluation: (1) the early childhood educator's (ECE) perception (perceived prosociality), (2) the children's own responses to hypothetical interpersonal problem-solving situations (expressed prosociality) and (3) observation of the children's prosocial behaviour during symbolic play with a peer (observed prosociality). In line with many studies in this field, the results show that girls are perceived by their ECEs as being more prosocial than boys. However, analyses of the data on expressed prosociality and observed prosociality did not reveal a significant gender effect. These results are discussed with respect to the influence that differential perceptions based on gender have on the assessment of children's prosociality. Some possible explanations for this gender gap, particularly in educational contexts, are put forward.