ADULT education is not good enough in the East Riding, says Ofsted.
A new report by Ofsted criticises the quality of teaching and assessment and the levels achieved by students.
It also says there needs to be improvement in the effectiveness of leadership and management.
The report, following a five-day visit to colleges and school offering adult education in November, states: "Overall, the quality of provision which the service offers has declined since the previous inspection and leaders and managers have been slow to improve this.
"The service is not sufficiently critical about its performance and has not recognised all its significant weaknesses."
On the positive side, the report recognises that people enjoy learning and the service's approach to making provision for different groups of learners is outstanding.
East Riding Council pointed out the inspection was carried out under the revised framework that had only been in place since September and which was devised to be a tougher test.
A spokesman said: "The provision for adult learning is made from a number of different strands.
"The work that is done through East Riding Training Services, supporting apprentices, was judged to be good and we are pleased that this was the case.
"The larger raft of provision is the Adult Education Service, which delivers courses and qualifications to a large number of adult learners and some pre-16 learners in a range of settings across the large rural area that is the East Riding."
He said adult education is provided in purpose-built centres to village halls.
"Everything from life drawing and pottery, right the way across to academic qualifications is offered as learners pursue their aspirations to attend university," he said.
"Inspecting such a range of provisions across the range of settings is challenging and Ofsted saw a snapshot of the working practice of the service."
Mike Furbank, East Riding Council head of achievement and inclusion, said: "We acknowledge that the inspectors saw some lessons that could have been better and were looking for assessment processes that better matched their requirements.
"We are already taking significant action to bring about improvement.
"The service has created an action plan with clear improvement milestones built in.
"We will be striving to be judged as good when Ofsted return."