School inspectors in England are warning of weaknesses in the first years of learning - with literacy and calculation "particular problems".
Inspectors examined the first steps in children's learning
Ofsted has examined a range of educational settings for three to five-year-olds, including schools, nurseries and children's centres.
Inspectors found that in a third of them, language and literacy were below the expected standard.
And by the age of five, boys had already fallen behind girls.
"Children's low achievement in early reading, writing and calculation in some settings must be tackled so they are able to achieve the best possible outcomes to set them on the right path for their future education," said Miriam Rosen, Ofsted's director for education.
The report from the education watchdog, based on visits to 144 different educational settings, examined young children's experience of the "foundation stage" of the curriculum.
While the inspectors reported good standards in the majority of cases, they warned there was "room for improvement".
"Literacy and calculation skills are a particular problem.
"Standards in communication, language and literacy were lower than expected and children's speaking and listening skills were weak in a third of the settings visited," said Ms Rosen.
"Significant barriers to learning in these settings included inadequate support for children who were at the early stages of learning English as an additional language, and high mobility in the communities they served."
Inspectors found that even by this early stage of children's education, girls had gained a clear advantage over boys.
"Girls reached higher standards than boys in all areas of learning.
"Girls applied themselves to desk-top work more readily than boys and were also keener to show their work and put their hands up in response to questions," said inspectors.
The report said boys were less likely to speak with confidence or to be creative in their language.
'Progress to make'
The study examined how children were learning in a range of different settings, from classes attached to primary schools through to private nurseries.
And there was criticism in the report for weaknesses in the continuity of teaching and learning when children moved between these sectors.
A recent study showed that after only a year in school, children from disadvantaged backgrounds were already discernibly falling behind, as measured by tasks such as writing their name or reading simple words.
Children's Minister Beverley Hughes said she was pleased the report showed that children were achieving well in most of the early learning goals.
"I recognise, however, that there is still progress to be made".