Do children use private information to their own advantage? Is this ability related to emotional intelligence? To answer these questions, we conduct a large lab-in-thefield experiment with 1662 participants from 8 to 18 years old who play a game with two-sided private information. We show that participants of all ages understand the fundamental relationship between action and private information. The ability to select payoff-enhancing strategies steadily increases with age but the capacity to recognize subtle variations in incentives triggered by changes in game structure remains elusive even for individuals at their peak cognitive capacity. Remarkably, participants of all ages who have heightened emotional intelligence exhibit a greater tendency to anticipate the behavior of others, best respond to them and, consequently, achieve higher payoffs. The paper thus reveals a strong, robust connection between affective and cognitive-theory-of-mind in young populations. It also highlights the importance of empathic skills for decision making.