The structure of marriage and child-rearing in U.S. households has undergone two marked shifts in the last three decades: a steep decline in the prevalence of marriage among young adults, and a sharp rise in the fraction of children born to unmarried mothers or living in single-headed households. A potential contributor to both phenomena is the declining labor-market opportunities faced by males, which make them less valuable as marital partners. We exploit large scale, plausibly exogenous labor-demand shocks stemming from rising international manufacturing competition to test how shifts in the supply of young ‘marriageable’ males affect marriage, fertility and children's living circumstances. Trade shocks to manufacturing industries have differentially negative impacts on the labor market prospects of men and degrade their marriage-market value along multiple dimensions: diminishing their relative earnings—particularly at the lower segment of the distribution—reducing their physical availability in trade-impacted labor markets, and increasing their participation in risky and damaging behaviors. As predicted by a simple model of marital decision-making under uncertainty, we document that adverse shocks to the supply of `marriageable' men reduce the prevalence of marriage and lower fertility but raise the fraction of children born to young and unwed mothers and living in in poor single-parent households. The falling marriage-market value of young men appears to be a quantitatively important contributor to the rising rate of out-of-wedlock childbearing and single-headed childrearing in the United States.