We examine how son preference affects women’s mental health across generations using original survey data from extended households in rural India. Leveraging exogenous variation in the sex of the firstborn child, we find that mothers-in-law (MILs) whose co-resident daughter-in-law (DIL) had a firstborn son face a 15 percent lower risk of anxiety or depression. In contrast, firstborn sex has no average effect on DIL mental health, although adverse effects of not having a son emerge among older DILs who face a closing reproductive window. We also find that a DIL’s firstborn son shifts MIL time allocation toward childcare and increases her support for DIL employment when children are young, boosting younger DILs’ labor force participation. These findings reveal an intergenerational pathway linking son preference to women’s mental health, intrahousehold dynamics, and economic outcomes beyond fertility alone.