The London Rebuilding Society, which makes loans to social enterprises, is seeking to attract community organisations in the capital to its mutual aid fund.
The fund was launched last October as a form of credit union for small charities interested in developing social businesses.
So far, eight community organisations have signed up, but the society hopes to attract about 50 in the long term.
"We did research with small voluntary organisations last year and found that most wanted to get away from grant dependency but did not feel they were yet ready for loans," said chief executive Naomi Kingsley.
Under the mutual aid fund, organisations invest in the society and, as an incentive, for every £4 invested the society gives them an extra £1 in bonus shares. The charities can then borrow against the assets of the fund.
The organisations that have so far signed up are mainly women-led community groups working in areas such as health, training and organic farming.
They have invested up to £600 each.
Members of the fund also receive advice and training from LRS on setting up businesses and how to make themselves sustainable.
One of the organisations to join the fund is Daintynak Performing School, a centre with 62 children drawn from the London boroughs of Newham and Westminster and Bexleyheath in Kent. The school hopes to borrow money to finance the buying of its own premises.