Parents want their children to be happy, educated, and successful, but are these goals related? People assume that success leads to happiness, but research on adults supports a reverse conceptualization: Happy people are more successful. Is happiness during childhood also linked to later success? Across the lifespan positive affect is linked with expanded cognitive abilities, learning, and resource building that can be adaptive and useful such that it leads to more success. Conversely, ongoing negative affect can reduce opportunities for growth and learning. Thus, happiness at any age may predict future success. Yet, no research has examined if positive and negative affect during infancy predicts childhood cognitive abilities and adult academics success. In a community sample, I hypothesized that higher infant positive affect (but not negative affect) would predict higher childhood cognitive abilities (i.e., IQ) and adult academic success (i.e., education attainment) in a 29-year study (n = 130). Positive affect, but not negative affect, during infancy (age 1.5), directly predicted higher childhood IQ (ages 6-8) and higher educational attainment (age 29), even after controlling for family socioeconomic status and infant intelligence. Childhood IQ partially explained the link between positive affect during infancy and adult educational attainment. This study advances understanding of how happiness during infancy (before formal education has begun) is linked to gold standard indicators of cognitive abilities and adult academic success. Parents, educators, and policymakers may want to place a higher value on early affective experiences when considering educational success. (PsycInfo Database Record (c) 2020 APA, all rights reserved).