This paper studies the impact of schooling intensity on students’ noncognitive skills. It exploits a major school reform that reduced total years in high school but retained the high school curriculum, thereby increasing weekly school hours. The sharp, regionally staggered one-year reduction in high school duration allows us to identify causal effects. Our results show that higher schooling intensity decreases overall students’ emotional stability but increases openness for disadvantaged students. Our finding that investments in cognitive skills can crowd out noncognitive skills is consistent with the predictions of our theoretical model, which imposes a per-period budget constraint for total investments in skill formation.