The agency has invaded vast tracts of the education landscape in what may be a search for a new purpose, as the frequency of school inspection is reduced from a four-yearly to a six-yearly cycle.
The power of Chris Woodhead, chief inspector of schools and head of OFSTED, now extends well beyond his principal duty to maintain a system of efficient inspection of schools.
Over the first four years of his tenure - now extended to 2003 - Mr Woodhead embarked on a number of initiatives that would not appear to be natural territory for OFSTED. The agency now has a stake in virtually every aspect of education policy: the curriculum, educational research, teacher training, local education authorities and pedagogy.
For example, Woodhead's advice to ministers on slimming down the primary curriculum seems to have been preferred to that of the Government's own curriculum advisers. The Qualifications and Curriculum Authority's concerns that such an emphasis on literacy and numeracy might result in a restricted, less balanced curriculum failed to win the day.
Mr Woodhead has also taken the initiative in questioning the relevance of educational research. Senior civil servants reacted with irritation to the revelation that OFSTED had commissioned James Tooley, from the right-wing think tank, the Institute of Economic Affairs (he has since been appointed professor of education policy at Newcastle University), to carry out a small-scale study of research articles that had appeared in education journals.
The Department for Education and Employment already had plans for a more thorough investigation of the usefulness of education research. In the end,both studies came to similar conclusions about the irrelevance of much of what passes for research.
Mr Woodhead's organisational skills have also been deployed to bring together headteachers and ministers in forging the first national consortium to provide school-based teacher training in primaries. The scheme had the added allure of being launched at a seminar for "beacon" schools at the Highgrove home of Prince Charles with David Blunkett, the Education and Employment Secretary, in attendance.
Critics of the consortium arrangement point out that school-based courses in secondary schools have not had favourable reports from OFSTED - and, more seriously, Mr Woodhead has now become directly involved in a project which his agency will have to judge. OFSTED is responsible for inspecting teacher training, and more reports have created turmoil in the sector.
For the past 12 months, OFSTED has had the added duty of inspecting the effectiveness of local authorities in raising standards in schools. This has meant working with a partner (the Audit Commission ) which has a track record of measuring the performance of public services. The exercise appears to have led to internal struggles between the two agencies, particularly over such high-profile and controversial reports as the inspection of Birmingham's education services.
While OFSTED has added local authorities to its inspection portfolio - much to the suspicion of directors of education who cite Mr Woodhead's public views that schools might better off without them - its workload in inspecting schools has eased and is likely to ease further. A "light-touch" approach to inspecting successful schools is to be combined with a more intense focus on those which are under-achieving.
OFSTED's forays into other areas may be a search for a new role, but Mr Woodhead has always apparently taken the view that there are no boundaries to his sphere of influence.
Under the previous administration, the chief inspector was closely involved in setting up the national literacy and numeracy centre. Reportedly, bypassing the customary policy routes, he took his idea direct to John Major.
The two centres have been instrumental in developing this Government's strategy for raising standards in primary schools. They are directed by the standards and effectiveness unit in the DFEE, but OFSTED continues to play a significant role.
Almost as a sideline, the office has produced videos intended to demonstrate the best primary practice in teaching reading and maths. The agency has also built up a database of good practice which draws on information from its inspections, and Mr Woodhead is known to favour more whole-class teaching in primary schools.
Such activity, says John Dunford, general secretary of the Secondary Heads Association, leads to a confusion of responsibilities for OFSTED. What concerns Mr Dunford is that the chief inspector persuades ministers to adopt a particular policy, and OFSTED is also the agency that monitors the policy's effectiveness. For example, OFSTED is monitoring the literacy strategy in schools and will take on numeracy when it is introduced next year.
A range of motives for Mr Woodhead's relentless pursuit of objectives beyond the legal duties of OFSTED have been mooted.
One view is that he is a man with a mission to root out what he sees as the progressive theories embedded in the whole system which have, in his opinion, damaged the education of children.
Last week, Mr Blunkett agreed that OFSTED should "refocus" its activities in response to "new circumstances and challenges". His letter of appointment set out more clearly than in the past the role that ministers expect OFSTED to play in the remit agreed for the next five years of Mr Woodhead's contract.
Co-ordination of the Government's policy to raise standards in schools is to be the responsibility of the standards and effectiveness unit. Officials in the unit will be expected to ensure that the Teacher Training Agency, the QCA and OFSTEDare working effectively towards that end. Whether the chief inspector's personal agenda will allow him to "work closely" with other agencies - as ministers hope and require - remains to be seen.