An "unacceptably" high number of people in England cannot read, write and count properly, MPs have warned.
They say poor teaching and a lack of understanding about what works to improve adult skills are to blame.
Education experts and late learners tell the BBC news website what schooling means to them.
PETER, 34, OLDHAM
When I was at school 20 years ago we were never encouraged to read books. In half a school year, we read just one book and it was read out loud. I didn't get much access to books. I didn't like school and was in the bottom of the class. The teaching wasn't at all pro-active and I found the classes boring.
Peter: To see my son read makes me feel brilliant
When I was 13 I had the reading age of a 10-year-old. I left school with two grade E passes in English which I only managed to get because my dad bought me a book on GCSE English.
When I left school I struggled to get a decent job. My poor reading skills put me off applying for jobs and courses. Then I had a girlfriend who was doing an English degree. I remember the day she took me to a bookshop: My life changed. I picked up "The Football Factory" by John King and I couldn't put it down; I got really interested because the subject matter grabbed me. Soon after, my brother lent me "Animal Farm" by George Orwell and I loved it.
I started to do an English course but unfortunately I couldn't finish it because it started to interfere with my job. But I taught myself to become more literate. I'm much more confident now and can take on more responsibility at work. My career has improved because of it.
I have a four-year-old son. Since he was six months old I have read to him every day for two reasons: Firstly to help me with my reading and secondly to share my love of books with him. He has loads of books and to see him read them makes me feel brilliant.
Hopefully, I've now given my son the basics. I can't remember my own parents reading to me. I think good literacy skills are a combination of two things: Parenting and good teaching at school. I've tried to instill a love of books in him from an early age. I've even got my wife interested in books now.
It's not what you read that's important, it's the reading itself that is.
I work with 16 to 18-year-olds on the Entry to Employment scheme. I see up to 40 young people every week who have left school with few or no qualifications. I am 56 years old and this is the first time I have worked with young people. I am surprised at how many come through the door. This is just one city and there are so many of them needing our help.
As they get a bit older, those who haven't done well at school realise that they have to do something about their situation. That's when you can get to work with them and get things done. If they don't do something, they'll have no future.
I think the young people I see are in this situation for a number of reasons: Teachers don't seem to have much authority or respect any more. I think the main reason though is upbringing. Many come from unstable backgrounds and haven't been brought up by their own parents. This is because mum and dad have been involved in drugs or crime. Some have no father figure and have gone off the rails. Many have been kicked out of home by parents because of rows.
Despite this, most young people who come to us make an effort and recognise the importance of having qualifications to improve their future.
I help on an adult numeracy scheme and it is amazing how badly people have been failed by their school experiences.
Young people who have not done well at school come to us because they recognise that to get a good job or to get a promotion, they need to get qualifications.
I think the main reason some children don't do well at school is the stress placed on teachers to reach targets. They feel under pressure to get children to pass exams, so if a child doesn't look like he or she will do well, the teacher will overlook them. Likewise with the very bright children, there is no capacity in the system to stretch them.
When I was young, I was struggling in school, so I had remedial lessons which helped me. Classes like that aren't an option any more so children get further behind. This is a systematic failing.
I believe that up to 90% of people I work with would have benefited from remedial help early on in their education. Once pupils have slipped through the net, it is very difficult to get them interested in education again.
We need more one-to-one teaching. The sooner governments stop regarding schools as sausage machines churning out students that conform rigidly to their targets, the better. It is good that money is being spent to help people who were previously failed by the system but please invest more time and money in the schools.
Numeracy is so important. It can improve your job prospects and make you a better functioning adult. Can you imagine not knowing whether you can afford to buy your child an ice cream and a cake because you can't add up the two prices?