A culture change in the penal system is needed to stop the rising number of suicides in prisons, according to a new report.
Campaigners say a "profound" shift is needed to move from a primarily punitive approach to one centred around rehabilitation and recovery.
Staff shortages and a "toxic" working environment were highlighted as issues in a paper published by the Centre for Mental Health and the Howard League for Penal Reform.
Figures published last month showed there were a record 119 apparent suicides in prisons in England and Wales last year - which is double the number in 2012.
There has also been a rise in self-harm incidents across prisons.
Frances Crook, chief executive of the Howard League for Penal Reform, said: "Overcrowding and understaffing in prisons is placing intolerable stress on staff and prisoners, and putting lives at risk.
"No one should be so desperate while in the care of the state that they take their own life."
Sarah Hughes, chief executive of Centre for Mental Health, said the new research shows that a new approach to suicide prevention is necessary.
She said: "We need to bring about a culture change in prisons that puts safety top of the agenda, that understands the traumas both prisoners and staff too often live with, and that means people get the right help when they need it."
A Government spokeswoman said: "All prisons have established procedures in place to identify, manage and help prisoners with mental health issues.
"Increased support is now available to those at risk of self-harm or suicide, especially in the first 24 hours, and we have invested in mental health awareness training for staff.
"An internal inquiry is also under way looking at all deaths in custody in the last year, to further our understanding of why these events happen."