Children's work habits at school include being a hard worker, turning in work on time, following classroom rules, and putting forward one's best effort. Models on youth character, noncognitive skills, and social-emotional learning suggest that self-management skills like work habits are critical for individuals' subsequent academic success. Using data from 1,124 children in the NICHD Study of Early Childcare and Youth Development (49% female; 77% White), we examined children's developing work habits from first to sixth grade and their developmental cascading effects on academic outcomes at the beginning and end of high school as well as at age 26. The findings on differential stability of work habits (i.e., bivariate correlations) suggest that children were likely to maintain their relative position among peers from first to sixth grade. The complementary findings on mean-level changes from the latent growth curves suggest that children's work habits exhibited mean-level increases over the same period, meaning that children's work habits became more advanced from first to sixth grade. Models used to examine the developmental cascades of work habits suggest that children's work habits at first grade and the growth in children's work habits from first to sixth grade (a) directly predicted their academic outcomes at the beginning and the end of high school, and (b) indirectly predicted their educational attainment at age 26 through their academic outcomes during adolescence. These findings underscore the importance of foundational noncognitive skills during middle childhood that predict individuals' academic outcomes up to 20 years later in adulthood.