This is the first study to offer evidence that happiness during infancy predicts childhood cognitive abilities and adult success.These findings are particularly important because happiness was measured before formal education begins, thus reducing directionality concerns and confounds from formal education. These findings support the broaden-and-build theory (Fredrickson, 2013) by offering indirect evidence that infant positive affect is associated with increases in intellectual resources (i.e., higher IQ scores) and greater educational attainment.