The sharing of skills, resources and experience can be made even more effective by the sharing of premises - it keeps costs low, too.
Some people still mistake the large building on South Street, in the bustling heart of Bromley, for the town's Magistrates' Court - because this is what it was until the mid-90s. Inside the building, however, the transformation is unmistakable. The old, austere courtrooms have been turned into light, airy offices decorated in pastel colours. There is a cafe, an information centre and a stream of people passing through the doors every day - not one of them summoned to trial.
This is Community House, home to the local branches of five charities - Age Concern, Relate, Deaf Access, Citizens Advice and Community Links.
The five chose to relocate some of their offices to the court's old cells, partly because of their sound-proofing and privacy. The idea originated at Community Links in 1999, when managers talked of bringing together a group of charities in one building to keep running costs low and enable local people to obtain help under one roof.
To do this, the charities established Bromley Voluntary Sector Trust, which secured the premises - at that stage empty and in a state of considerable disrepair - from Bromley Council on a 25-year lease. They refurbished the building with the help of the council and National Lottery funding.
In 2000, the charities moved in to the newly named Community House, which is today managed by the trust. As well as the five charities' offices, the trust rents out low-cost office space to voluntary organisations and offers local groups the use of its meeting rooms, conference facilities and cafe. It is, as one local newspaper put it, "the jewel of Bromley's voluntary sector".
Community House manager David Sadler, who is employed by Bromley Voluntary Sector Trust, says the partnership has many advantages. "Each of the charities is now based in vastly improved premises," he says. "And having five major organisations under one roof makes referrals between them much easier - the services they provide complement one another."
He adds that being based in a well-known, easily accessed building is good for the charities' profiles, in terms of both fundraising and the ease with which service users can reach them.
Julie Fuller, chief executive of Community Links, an umbrella group that promotes involvement in local charities, agrees. "We would never have been able to afford a central location like this by ourselves," she says.
"Most local bus routes come right into town, so it makes us much more accessible to the general public. When people get to know about one charity, they get to know about the others."
There are other practical advantages, she says: "It's particularly beneficial to have meeting rooms and the cafe. The charities based here are some of the largest, and the co-location is extremely useful."
Fuller believes that a set-up such as Community House has advantages beyond the immediate work of the groups involved. "I think there is potential in something like this for raising the profile of the voluntary sector as a whole," she says.
For Deaf Access, the benefits can be measured in straightforward terms.
The charity, which runs a drop-in service for deaf people to get advice and support on everything from jobs to equipment, used to be based in a local hospital. Before it moved to Community House, it had 2,250 visitors who needed its help and services every year - in the first year at Community House, this grew to 4,300.
The service it is able to offer those visitors has been enhanced, too, says its manager, Sue Craney. "As a small charity, we benefit from the experience, knowledge and training offered and shared by partnerships with the other charities," she says. "And our expertise in deaf issues means we can offer them advice and assistance in turn - it's a mutually beneficial relationship."
The only problem with such a scheme affects all charities. "We are all stretched financially," she says. "So there is no money available for team-building events where we can all meet."
The only real challenges faced by Community House were associated with its establishment and were temporary. The charities involved say it took a significant amount of time and manpower to turn a crumbling building into the thriving centre it is today. At first, it was run by one of the charities' trustees, but Sadler now manages the building alongside a balanced board of 11 trustees - six independent and one from each of the tenant organisations.
"It's been a great success", says Craney. "Community House is a great place to work."
- Julie Fuller, chief executive, Community Links
"Be aware of the demands, the time and the amount of work that can be involved in a partnership like this. You need to be very clear about how it is going to be run - by one organisation or a separate legal entity? Be aware of the danger that, in some circumstances, a charity could lose sight of its real work."
- David Sadler, manager, Community House
"It is important to get someone involved who is not associated with the individual charities. You need someone who can look at the bigger picture, who won't put one charity's interests first and who won't be parochial."