The scheme covers 30,000 pupils in primary years P1 to P3, aged between four and seven, in the Borders, East Ayrshire, Fife, Glasgow and West Dunbartonshire.
The universal free meals scheme aims to promote social inclusion and improve children's health, and it is hoped to increase school attendance and achievement. The pilot will be evaluated to monitor any changes in children's attitudes and behaviour, any uptake in school lunches by the pupils taking part, and any practical issues for councils and schools that are flagged up by the scheme's implementation.
The cost of extending the scheme across the country has been estimated at up to £46m.
A spokesperson from the Scottish Executive said, 'The decision about what happens after the pilot will take place in March 2008, and will depend on the outcome of the pilot scheme's evaluation.'
John Dickie, head of the Child Poverty Action Group in Scotland, said, 'Universal free school meals could make a huge impact in tackling family poverty and improving children's health and ability to learn.
'The sooner the Scottish government rolls out free school meals, the better, so it is vital that the pilot programme succeeds. Providing high-quality, nutritious meals in attractive surroundings and ensuring that pupils, teachers and parents are involved in the pilots at every stage will be crucial to that success.'
A similar scheme was run for three years by Hull City Council and an interim report found that it made a significant impact across the city, with calmer classrooms and children who were more aware of healthy eating. The Hull scheme ended in summer 2007 when the new Liberal Democrat administration decided not to continue the project on the grounds of cost.
The evaluation of the Scottish scheme is to be published in summer 2008.