The First Minister used a debate on independence at the Scottish Parliament to announce a £114 million package of support for children which will start before the referendum.
In the first step, from August, an extra 8400 two-year-olds - from families where no-one is in work - will qualify for 600 hours of free childcare per year.
A further 7000 two-year-olds, from families on a range of benefits, will be entitled to the care from August next year. By then, 27% of all two-year-olds will be entitled to the hours.
The First Minister also confirmed all P1 to P3 pupils will be offered a free school meal, as revealed in yesterday's Herald.
The move, which was welcomed by campaigners, follows a similar announcement in England. It will begin in January next year at an annual cost of £42m.
Mr Salmond said providing free meals for all P1 to P3 pupils would improve their health and education while saving families at least £330 per child per year.
But he claimed only a Yes vote would enable the Scottish Government to fund a much bigger expansion of free childcare promised in its White Paper on independence.
He told MSPs: "These are important and immediate announcements, but they fall short, I readily admit, of the transformation that is required in Scottish society."
Legislation currently going through Holyrood will provide all three and four-year-olds, plus the 3% of Scots two-year-olds in care, with 600 hours of free childcare.
If voters back independence, the SNP have promised to provide 1140 hours of free childcare - the same time children spend in primary school - for all three and four-year-olds and vulnerable two-year-olds by 2020.
By 2024, all children aged from one to four will be entitled to near full-time care. The SNP insist the £1.2 billion scheme would pay for itself by allowing more women to take jobs, generating extra income tax and cutting the benefits bill.
Offering free school meals to all P1 to P3 pupils fulfils an SNP election pledge dating back to 2007.
The Scottish Government has come under growing pressure to keep its promise since September, when Deputy Prime Minister Nick Clegg used a speech in Glasgow to announce free meals for all children in the first three years of primary school in England.
Campaigners voiced their delight. John Dickie, head of the Child Poverty Action Group (CPAG) in Scotland, said: "A universal approach to healthy free school lunches provides a huge boost to children and parents at a time when they are under increasing pressure from tax credit and benefit cuts, soaring food and energy prices and stagnating wages."
Professor Christopher Chapman, director of the Robert Owen Centre for Educational Change at Glasgow University, said: "This is a major step forward in not only recognising but also tackling the relationship between low educational outcomes and issues of health and wellbeing."
The move was also welcomed by the GMB union and children's charity Children in Scotland, who were among a powerful coalition of bodies - including the Kirk - lobbying for free meals.
However, Scottish Labour said the money should have been spent on a bigger expansion of childcare, rather than free school meals.
Education spokeswoman Kezia Dugdale said: "The key question from today's announcement is -how many of the poorest kids will be better off as a result of extending free school meals? The answer is not many, as the poorest 20% of kids already get free school meals.
"Within Scottish Labour, we don't disagree with the free school meals policy, but believe the money could be better spent by providing childcare for the poorest 50% of two-year-olds."
She added: "The SNP have been telling us childcare was their top priority. Alex Salmond's announcement today is sadly a big opportunity missed."
The £114m, over two years, includes £55m on free meals and £59m extending free childcare.