Significance The belief that investing in child health and nutrition can generate improvements in individuals’ future quality of life is the rationale for many policy initiatives around the world. Yet there remains limited evidence on the causal impacts of child health gains on adult living standards, especially in developing countries. This study contributes evidence that addresses leading methodological concerns, by using variation in child health via a randomized health intervention that provided deworming treatment to Kenyan children. We estimate impacts on individual living standards up to 20 y later among a representative sample of participants, and find those in the deworming treatment group experience meaningful gains in adult living standards and earnings, and shifts in sectors of residence and employment.