This is the first article examining the causal impact of mandatory extended primary schooling on happiness (sense of well-being) of young adults. We rely on a law change that raised compulsory schooling from 5 to 8 years in Turkey to address the endogeneity of education to happiness. Our study shows that, for females, earning at least a middle school diploma increases the likelihood of being happy and the probability of being satisfied with various life domains. Descriptive tests suggest that being hopeful about one's own future well-being partly explains the relationship between women's schooling and happiness. For males, although relatively imprecisely estimated, we find evidence that earning at least a middle school degree results in a decline in subjective well-being. Supplemental analysis develops evidence consistent with the view that an imbalance between aspirations and attainments, flowing from extended primary schooling, may be the reason behind this counterintuitive finding among men.