Using PISA 2018 data from nearly half a million 15-year-olds across 72 middle- and high-income countries, this study investigates the relationship between economic development and adolescent subjective well-being. Findings indicate a negative log-linear relationship between per-capita GDP and adolescent life satisfaction. The negative nexus stands in stark contrast to the otherwise positive relationship found between GDP per capita and adult life satisfaction for the same countries. Results are robust to various model specifications and both macro and micro approaches. Moreover, our analysis suggests that this apparent paradox can largely be attributed to higher learning intensity in advanced countries. Effects are found to be more pronounced for girls than for boys.