The Netherlands, followed by Sweden, Denmark and Finland, finished at the top; the United States was 20th, and Britain was 21st, the report released Wednesday by UNICEF said.
Researcher Jonathan Bradshaw said children fared worse in the United States and Britain -- despite high overall levels of national wealth -- because of greater economic inequality and poor levels of public support for families.
"What they have in common are very high levels of inequality, very high levels of child poverty, which is also associated with inequality, and in rather different ways, poorly developed services to families with children," said Bradshaw, a professor of social policy at the University of York in Britain.
"They don't invest as much in children as continental European countries do," he said, citing the lack of day-care services in both countries and poorer health coverage for children in the United States.
The study also gave the United States and Britain low marks for their higher incidences of single-parent families. Britain was last, and the United States was second from the bottom in the category based on the percentage of children who lived in single-parent homes or with stepparents, as well as the percentage who ate the main meal of the day with their families several times per week.