Good early-years education, from the age of two, improves children's intellectual development in their first two years at school, according to Government-commissioned research.
The latest phase of the Effective Provision of Pre-school Education Project (EPPE) found that effective pre-school experiences have lasting effects on achievement and have a major impact at least until the end of key stage 1.
Disadvantaged children benefit the most, both academically and socially, especially when they mix with peers from a wide variety of backgrounds.
However, children from less advantaged homes tended to attend pre-school for four to six months less than other children.
The longitudinal study of 3,000 youngsters assessed three and four-year-olds to create an individual profile, and again at entry into school, to compare their progress. Further assessments were carried out at the end of Years 1 and 2.
Researchers led by Professor Kathy Sylva, from Oxford university, found that children who had attended some form of pre-school had better all-round development than those who had not attended any.
Children who started early-years education before they were three showed better intellectual development. Those who attended part-time benefited as much as those who attended full-time.
Overall, children's language and reading ability was shown to benefit from pre-school education, and behaviour and social skills improved. Social development was better among girls than boys in this age group.
The study found that there were "significant differences" between individual settings and their impact, with some being more effective than others. Nursery schools and settings which combined care and education were the best.
The benefits continued into key stage 1, with children making more progress academically.
Researchers found that the quality of pre-schools affected children's scores on standardised tests in reading and mathematics at the age of six.
However, these effects were less noticeable at age seven.
Children who had been in pre-school education were also more independent and less anti-social in primary schools.
The study noted that "where staff showed warmth and were responsive to the individual needs of children, they made more progress".
Children also made more progress if their parents read with them, taught them songs and nursery rhymes, played with letters and took them on visits to libraries. Parental involvement helped to reduce the chances of children developing special needs.
Researchers said that where early-years provision was weaker, better training for staff was needed. They found that knowledge of child development "is often weak among early-years staff".
"Staff need a good grasp of the appropriate pedagogy for a child's understanding and interests to develop fully," the study said.
The most effective pedagogy combined both teaching and instructive play activities, it said.