Putting more investment into early years and then focusing on disadvantaged pupils in compulsory education are the key ways of improving children's well-being in the long term, a new report comparing 30 countries has found.
Researchers at the Organisation for Economic Co-operation and Development said that resources should be prioritised in the first six years of life to help children become happier.
The report, Doing Better For Children, found that children in the UK had a high quality of school life and were more likely to enjoy school and less likely to report bullying than elsewhere.
But despite living in a country where family income is higher and child poverty lower than average for industrialised countries, overall child well-being in the UK was low.
This was largely due to high rates of underage drinking, particularly among girls, and one of the highest teen pregnancy rates. There is also a high proportion of young people not in school, training or jobs.
The report calls for more attention to be paid to improving life for the youngest children to improve well-being in the long term.
In the report, co-author Dominic Richardson writes: "The UK stands out as increasing early investment in recent years, but reinforcement of this trend for disadvantaged older children is also needed."
The report points out that higher-performing teachers are often rewarded by getting the better job of teaching school-ready, well-adjusted children rather than being paid more to teach struggling children. This is a process that can reinforce inequality between advantaged and disadvantaged children.
It suggests that research backs having the best teachers working in schools where students are at highest risk. One option it highlights is pay premiums, which are used in the US for teachers working in disadvantaged schools. It's also something that has been mooted here by both the Liberal Democrats and the Conservatives.
The report uses figures from 2003, when the UK government spent approximately pound;90,000 per child from birth to the age of 18, compared to an average of just under pound;80,000.
It found that spending on early years varied hugely, with Hungary, Finland and Slovakia allocating a third or more of its childhood spending to this age group. On average, 40 per cent of spending on children went to the over-11s.
Megan Pacey, chief executive of Early Education, a campaigning group, said: "There is too much of a patchwork of provision in early years, with the quality of the setting dependent on your postcode and not consistent. I would encourage the current government and any future governments to take significant notice of these recommendations."
Children's minister Dawn Primarolo said: "We know childhood isn't good for every child and we will continue to focus on the problems that exist for some, while celebrating the many."
Shadow schools minister Nick Gibb said: "The OECD is right that money needs to be targeted at poorer pupils if we are to close the educational gap between the top and the bottom.
"That is why two years ago the Conservatives proposed education reform with an explicit pupil premium attached to children from less well-off backgrounds."