Many previous studies have found that children understand much earlier what a character who has a false belief will do than what a character will feel. This gap between the understanding of action and emotion is known as the belief-emotion lag and to this day there is no convincing explanation as to why it happens. There are also no studies that have explored whether this same gap occurs in the understanding of desire. This longitudinal study had a twofold objective: to explore the existence of a lag between the prediction of action and emotion based on desire, and to search for the role that specific emotions could have in children’s answers. To this end, we administered the Test of Emotion Comprehension (TEC) and the Theory of Mind (ToM) scale items to 103 children initially aged three years during the three courses of early childhood education.Results confirm the existence of a lag between the prediction of action and emotion based on desire. Besides replicating the well-known belief-emotion lag, we found that performance in prediction of emotion based on belief differed according to the emotion in question. Our discussion on the relationship between emotional and mental states knowledge suggest that the asynchronous development of emotional knowledge is a key point in understanding the lag. We also point out the limitations of the tasks and the instruments we use to evaluate emotion understanding in young children and suggest that researchers might use a broader and more functional approach to emotional development.