Childhood poverty increases the likelihood of adult poverty. However, past research offers conflicting accounts of cross-national variation in the strength of-and mechanisms underpinning-the intergenerational persistence of poverty. Here the authors investigate differences in intergenerational poverty in the United States, Australia, Denmark, Germany and the United Kingdom using administrative- and survey-based panel datasets. Intergenerational poverty is decomposed into family background effects, mediation effects, tax and transfer insurance effects and a residual poverty penalty. The intergenerational persistence of poverty is 0.43 in the United States (95% confidence interval (CI) = 0.40-0.46; P < 0.001), compared with 0.16 in the United Kingdom (95% CI = 0.07-0.25; P < 0.001) and 0.08 in Denmark (95% CI = 0.08-0.08; P < 0.001). The US disadvantage is not channelled through family background, mediators, neighbourhood effects or racial or ethnic discrimination. Instead, the United States has comparatively weak tax and transfer insurance effects and a more severe residual poverty penalty. If the United States were to adopt the tax and transfer insurance effects of its peer countries, its intergenerational poverty persistence could decrease by more than one-third.