Singing in groups can help people recover from mental illness, making them feel valued and increasing their confidence, according to research.
A University of East Anglia study of singers involved in free weekly workshops in Norfolk found benefits to mood and social skills.
Researchers said the Sing Your Heart Out project had stopped some people from relapsing.
They urged other areas to consider running community singing groups.
The Sing Your Heart Out (SYHO) initiative started in 2005 at a psychiatric hospital in Norwich, before branching out into the community.
It is aimed at people with mental health conditions as well as the general public, and regularly attracts hundreds of people to four weekly sing-alongs.
One of them is Penny Holden, 67, who has lived with bipolar disorder all her life.
She credits the singing group with turning her life around 13 years ago, when she was at her lowest.
She said singing in harmony had been a wonderful tonic.
"It's the best thing I've ever done. It's such a nurturing environment, where we look out for each other and help each other.
"I found it difficult to relate to people and trust them when I first went along, but I knew I wanted to do something to get involved in life again.
"But I didn't want to sit around talking and drinking tea and biscuits."
Researchers from UEA's Norwich Medical School said a study of 20 members of the group over six months found singing and mixing socially had helped those who had had serious mental health issues to function better in day-to-day life.
Lead researcher Prof Tom Shakespeare said it was "a low-commitment, low-cost tool for mental health recovery within the community" because it gave participants a feeling of belonging and wellbeing.
He said the breathing involved in singing had also been shown to be good for the body.
Prof Shakespeare said the term "choir" had been intentionally avoided in SYHO because it scared people off.
"Anyone can make a noise. No-one is ever rejected in these groups.
"There's also very little pressure because the participants are not rehearsing towards a performance."
This approach, he said, meant the singing groups were very inclusive, relaxed and fun.
And, in contrast to music therapy, there is no pressure for anyone to discuss their condition.
"That means you don't know who you're sitting next to. You don't have to tell anyone about yourself," Prof Shakespeare said.
As part of their study, the researchers organised focus groups with singers, organisers and voice coaches, who lead the groups and are paid from a community fund.