By the age of three, children from disadvantaged homes are up to a year behind in their learning than those from more privileged backgrounds.
Children were given a series of 'school readiness' tests
Graduates' children were seen to be 12 months ahead of those of the least well educated in tests on their grasp of letters, numbers, colours and shapes.
And disadvantaged children's vocabulary skills were 10 months behind their more advantaged peers, the study added.
The Institute of Education research was based on a survey of 12,000 children.
In the longitudinal study of children born in 2000 to 2002, girls were educationally three months ahead of boys on average.
The Millennium Cohort Study also found large differences between children living in families above and below the poverty line.
The poorest children were 10 months behind their wealthier peers in tests of their grasp of shapes, numbers, letters and colours known as "school readiness" tests.
And they were five months behind their wealthier peers in vocabulary tests.
One of the researchers, Professor Heather Joshi, said: "The advantaged children tended to be way ahead of the average and the disadvantaged children were lagging behind.
"If you look at the front runners and the runner ups - there's almost a year's worth of differences."
'Scots children advanced'
These results will not be a surprise to education experts or government policy advisers who have long known that parents' educational achievement and family income are indicators of a child's educational success.
But the research shows the scale of the differences in the educational achievement of different social groups at this early age.
A series of government initiatives, including providing free part-time nursery education to three and four-year-olds and efforts to get more parents reading with their children, aim to close the attainment gap between the rich and poor.
Schools minister Jim Knight said: "Closing attainment gaps between different groups of children is a massive priority for us.
"We are working hard to provide a range of support - such as catch up lessons, one-to-one tuition and wraparound support for children and their families.
"We provide a wide range of funding and support to help schools make sure that no child is left behind at any stage, whatever their background, gender or ability."
The study also suggested that Scots children were three months ahead of the UK average in their language development and two months ahead in "school readiness".
The research also highlighted marked ethnic differences, with a quarter of the black Caribbean and black African children who took the school readiness tests showing delayed development, compared with only 4% of white children.
Bangladeshi and Pakistani three-year-olds also recorded relatively low scores on both tests.
But research director of the study Dr Kirstine Hansen stressed the tests may not be a fair indicator of ethnic minority children's current or future ability.
"Before drawing firm conclusions we will need to investigate the circumstances in which the assessments were done, allowing for whether children lived in homes where English was not the main language spoken."