Her decision was denounced by the right-wing Centre for Policy Studies as an attack on Britain's intellectual culture. But the National Union of Teachers said it did not go far enough and should be extended to cover the full 14 to 19-year-old age range.
The NUT's view is echoed by many educationists who fear the review will fail to bring about radical change.
The Education Secretary, made clear at the Secondary Heads Association conference at Warwick University on Monday that the three-track qualifications system was here to stay. "GCSEs, General National Vocational Qualifications and National Vocational Qualifications must be rigorous. And they must be seen to be so. Let me be perfectly clear - nothing will be allowed to get in the way of protecting the rigour and depth of GCE A-levels; and nothing must distract us from the programme of work to develop and improve the GNVQ," she said.
And she said afterwards: "We do not want to tamper with a successful formula. But if we are looking at the overall menu, then what employers tell us is that young people fed on a diet of just A-levels don't have a rich and large enough menu."
She said "core skills", similar to those in GNVQs, could be studied alongside A-levels, and suggested students might take one A-level, two AS-levels in one year and study core skills in information technology and possibly a language or maths.
But she said that although she was not an enemy of modular A-levels (examining A-levels in units instead of by one terminal exam), she was worried about "creeping modularisation" which had led to concerns about rigour and standards.
She also stressed in her speech that she wanted to work with the broad consensus in favour of a review, notably the signatories to the joint statement on a coherent 16 to 19 education system last year - the Headmasters Conference, the Girls' Schools Association, SHA, the Association for Colleges, the Sixth Form Colleges Association and the Society of Headmasters and Headmistresses in Independent Schools. That joint statement also wanted to protect A-levels.
The Confederation of British Industry welcomed the decision and the Sixth Form Colleges Association called it "very encouraging."
John Cassels, director of the National Commission on Education, said that although he was "very pleased" to hear the announcement: "I hope Sir Ron Dearing will be radical. The needs of students are paramount. The present so-called three-track approach will not do. The National Commission on Education has proposed a high quality general education diploma which will enable all students to advance side by side, accumulating credits as they progress and with their achievements properly credited. We must finally get away from gold standards for the academic and a condescending pat on the head for the rest. Sir Ron is the man to sort all this out."
Ken Spoors, a lecturer and research officer a the post-16 education centre at London's Institute of Education, said: "The curriculum review was a picnic compared to post-16 and this is a remit with a ring of barbed wire."
He fears Mrs Shephard's words may signal "a limited flexibility solution" in an attempt to bolster the three-track system and relaunch ailing GNVQs.
The Education Secretary's mention of rigour was Tory code for subject specialisation, he said. The Tories believed standards could only be maintained through specialisation, whereas this narrow view was not prevalent on the continent, said Mr Spoors, .
John Dunford, the Secondary Heads Association's in-coming president and the author of a report proposing an advanced diploma which would include a mix of A-levels, shorter academic courses and vocational qualifications, said: "We are hoping that Sir Ron Dearing will take a broad view of his remit and include a review of key stage 4.
"We hope it will be possible for him to produce recommendations that will link A-levels and GNVQ so closely together that the step from being a unified system with two separate pathways to the eventual removal of the two titles can easily be made."
But Professor Alan Smithers, director of the Centre for Education and Employment Research at Manchester University, wants to keep the three tracks because he believes students should be able to choose their preferred routes at 14 years old. However, he wants the three tracks scrutinised and he would like to see more students taking AS and A-levels.
He envisages 17-year-olds studying five subjects, pursuing three or four to A-level and the remainder to AS-level.