Many schools already test their new arrivals each September, but this term it becomes a legal requirement in England and Wales for the first time. Ministers say baseline assessment will help teachers plan each child's future education, and help identify problems requiring extra attention early on.
Charles Clarke, the schools minister, said: "It is vital that children are taught according to their needs. Baseline assessment will enable teachers to know within weeks of children starting school how best to develop their individual pupils' potential."
Teachers have seven weeks to complete the assessments, the results of which will be collated by education authorities and the Qualifications and Curriculum Authority.
But there have been warnings about the quality of some of the assessment schemes being used. Professor Geoff Lindsay, of Warwick University's Institute of Education, has claimed that barely a handful of the 90 schemes approved by the QCA have been properly researched and validated.
There are also concerns that boys may be "written off" in their first term, because of their poorer performance compared to girls. A scheme used by Durham Council assessed twice as many boys as girls to be in the bottom attainment category.
But governors' organisations - whose members have to choose the schemes used by their schools - say baseline assessment is a building block for future educational success.
"Tracking children through school is of key importance if we are to ensure that they do reach their full potential," said Pat Petch, chairwoman of the National Governors Council.
She is confident that arrangements are in place in schools for baseline assessment to get off to a good start.
The Government has set aside Pounds 9.4 million from its standards fund for this term's exercise.
Children will be assessed on recognising and writing numbers one to 10, writing and spelling their own names correctly, recognising letters by shape and sound, and being able to concentrate on something without supervision for 10 minutes.
Schools are expected to discuss assessments with parents, who have the right to request their child's results. School results will be passed onto education authorities for collation, with grant-maintained schools passing their assessments directly to the QCA.
Men are in danger of being left out of the national childcare strategy, warns the Equal Opportunities commission. It says the Government must do more to recognise the role of fathers and recruit more men as childcare workers. It claims that at present low pay and and low status means men are unlikely to see childcare as an attractive career option.
"Given the widely held presumption that only women are suitable for this kind of work, it is not surprising there are very few men in the childcare profession," said an EOC spokesperson.