More than one million adults have addressed their learning "gremlins" by gaining a basic qualification in English or maths, the government says.
Participation in learning basic skills has greatly increased
Education Secretary Ruth Kelly said the stigma surrounding poor basic skills had been broken.
But she said 5.2 million adults in England still had literacy levels below those expected of an 11-year-old.
The media campaign urging adults to eliminate their learning gremlins had attracted many more learners, she said.
Adults taking a Skills for Life qualification can take a Level 1 qualification, equivalent to a GCSE pass at grades D to G, or a Level 2 qualification, equivalent to a GCSE pass at grades A* to C.
According to government figures, an estimated 5.2 million adults could not achieve the standard of literacy expected of an 11-year-old.
The figures show more than four million have taken up courses since 2001.
Speaking at the Skills for Life conference in York, Ms Kelly said 1,130,000 had achieved at least Level 1.
In the last academic year, half the qualifications involved literacy, 43% numeracy and 7% language courses for those for whom English is not their first language - markedly down on the previous couple of years.
"Four years of hard work on, Skills for Life is really bearing fruit, and having a positive effect on the lives of learners," Ms Kelly said said.
"The difference being made to people across the country is a real and enduring one."
Her department said later that, of the four million who had taken courses, 31% were aged 16 to 18 - included in the definition of adults.
It was not immediately able to say what proportion of those who had achieved Level 1 were teenagers.
A year ago the National Audit Office praised ministers for reaching its target of 750,000 adults in England gaining basic qualifications.
But it said "more than half" the qualifications involved had been achieved by learners aged 16 to 18.
Under new funding arrangements for further education courses announced last month, many adults will pay a higher cost for their courses.
Ms Kelly was speaking on the same day colleges presented a petition to Downing Street calling for the protection of such courses and for equal funding between schools and colleges.
But adults learning basic skills will still be entitled to free training.
Quality of teaching
The director of research and development at the National Institute for Continuing Adult Education, Peter Lavender, said the government had made a lot of progress in training adults with poor basic skills.
It was one of the government's "unsung successes", he said.
"We are delighted that millions of people are doing something about learning basic skills."
But he said the quality of teaching needed to improve.
"We have driven up participation, but our biggest challenge for the future is to improve the quality of teaching," he said.
Some of the best teachers were needed to teach challenging adults basic skills, he said.
A recent Ofsted report said the proportion of unsatisfactory provision in the rapidly expanding sector was "unacceptably high".
And he said in the future it would prove difficult to attract those adults who had a poor experience of school.
But encouraging learning through the workplace was the best way to reach people who needed to improve literacy and numeracy.
Releasing staff for courses would benefit all concerned, he said.
But a greater focus on learning numerical skills was needed, as there was a strong correlation between numerical skills and future earning potential, he added.
"And we know there is a significant issue with regard to understanding personal finance.
"People need to be able to understand pensions and loans, for example."