David Sherlock, head of the Adult Learning Inspectorate, says the companies and charities which provide work-based learning are getting to grips with the complex world of post-16 education.
He told the Association of Learning Providers' conference this week that they have improved each year since the Learning and Skills Council was created in 2001. Then, most work-based learning providers were unsatisfactory.
After the conference, he told FE Focus: "Work-based learning has come of age. One in three providers was inadequate but that compares with 46 per cent last year and 60 per cent the year before that, and this is the first year that the really good performers outnumber the poor."
He said the ALI's strategy of following up inspections with support for struggling training organisations has paid off because his team had "added value" rather than simply leaving them isolated.
The inspectorate has special advisers who work with providers who are due for reinspection so changes can be made step by step to ensure improvement.
Mr Sherlock said there is evidence that work-based providers are getting to grips with the wider lifelong learning sector created by the establishment of the Learning and Skills Council in 2001.
He says they have learned to work more effectively in partnership with the many organisations involved in vocational education.
Ivan Lewis, the minister for skills who was also at the ALP conference, confirmed that the Department for Education and Skills is about to announce a new "protocol" on a free market in vocational education. This should make it easier for the best private providers to compete for government funding for teaching NVQ level 1 and 2, and basic skills.
In his annual report, Mr Sherlock said: "Private training providers have taken the call to raise their game seriously and are now a worthy part of publicly-funded provision."