Happiness is generally considered an emotion with only beneficial effects, particularly in childhood. However, there are some situations where the style of information processing triggered by happiness could be a liability. In particular, happiness seems to motivate a top-down processing style, which could impair performance when attention to detail is required. Indeed, in Experiment 1, 10- to 11-year-old children (N = 30) induced to feel a happy mood were slower to locate a simple shape embedded in a complex figure than those induced to feel a sad mood. In Experiment 2, 6- to 7-year-old children (N = 61) induced to feel a happy mood found fewer embedded shapes than those induced to feel a sad or neutral mood. Happiness may have unintended and possibly undesirable cognitive consequences, even in childhood.