The Government's Big Society can be partly built by those excluded from it - prisoners, a charity has said.
The Prison Reform Trust published a report saying convicts need to be encouraged to volunteer and "active citizenship" should be promoted behind bars.
The charity said such a move would help make "prisons places of hard work and purposeful activity." Justice Secretary Ken Clarke has said many prisoners are living a life of "enforced, bored idleness".
The report, Time Well Spent, was based on survey responses from 82 prisons across England and Wales, and interviews with staff and prisoners in 12.
It found the "large majority" provide some opportunities for active citizenship - 95% of prisons have "race representatives" and 89% have "Samaritan Listeners". But overall, the report shows, volunteering is open to very few prisoners.
Prison Reform Trust chairman Lord Woolf said: "Every now and then, very good things happen in prisons.
"There are prisons where there are very good schemes, where they will make prisoners take responsibility. Sometimes it's done by arranging opportunities for prisoners and their victims to meet. Sometimes it's by ... training people to help those who are in danger of taking their own life."
A Ministry of Justice spokeswoman said: "This report echoes our plans to reform the justice system by turning around the lives of offenders so that they become contributing members of society.
"Volunteer work already takes place, for example reparative projects within prisons, that benefit local communities and through mentoring fellow prisoners with poor literacy skills.
"There is more to do. We intend to make prisons places where more and more prisoners take up challenging and meaningful work, learning the discipline of regular working hours and developing the skills to get off welfare and into legitimate employment."