Extended schools, where pupils can attend breakfast clubs and after-school activities, are said to improve GCSE results more quickly than the average.
Children can stay in school after lessons have finished
The government says this endorses its plan for all England's schools to provide extended services by 2010.
Researchers particularly highlighted the benefits for children who were eligible for free school meals.
These schools make a "real difference" for poorer families, says Alan Dyson of the University of Manchester.
Researchers from Manchester and Newcastle universities carried out a three-year study of extended schools - which have been piloting ways of supporting families beyond formal lessons during the school day.
They examined the "full service" type of extended school, which provides childcare and support before and after school - usually between 8am and 6pm.
Researchers found that the number of pupils getting five good GCSEs at extended schools rose by five percentage points between 2005 and 2006 - compared to a national average of 2.5 points .
In particular, the study found that extended schools were most beneficial for pupils from the most disadvantaged backgrounds, providing stability and helping to improve their chances of learning.
The study found that the gap in performance between pupils eligible for free school meals and those who were not had narrowed.
"Our evaluation shows that it is possible for schools and their partners to make a real difference to the life chances of disadvantaged children and adults," said Professor Dyson.
The research also suggested a positive impact on the wider community, with parents and other adults "beginning to see themselves as learners".
The idea of extended schools, with so-called "wrap-around" provision, was launched in 2003.
The initial wave of schools was given between £63,000 and £162,000 each per year to fund these services.
For an academic year, this means the extra hours could cost up to £4,000 per week per school.
The report says the project does have high costs - but concludes that there are also high benefits.
The schools included in this initial phase were typically in poorer areas, many with high rates of street crime - and the intention has been to use the security of the school environment as a constructive alternative to children roaming the streets.
This has been part of the growing cross-over between schools providing formal lessons and a wider range of social care - with staff such as mentors, family liaison officers and outreach workers operating from schools.
The extended schools project is to be expanded to all schools by 2010, but the level of extra provision will vary between schools - with over a £1bn already earmarked.
"We can see already the advantages this will have for all children, not only by allowing them to take part in different activities but also in helping them do better in exams," said the Children's Minister Beverley Hughes.