The anonymous private donor left the organisation £940,502 in her will, written in September 2003. She specified that the cash was to be used to encourage people to include charities in their wills.
It is the first time that Remember a Charity, the largest consortium of charities in the UK, has received a legacy. The organisation campaigns to encourage the public to think of a charity when writing a will, but does not solicit legacies for itself or specific members.
How the money should be spent will be decided after discussions with the body's 140 members and a consultation with the Charity Commission.
It is not yet clear whether funds will be divided among member charities to use in individual campaigns or whether the cash will be used for an initiative similar to the coalition's 2006 television and press campaign, which bore the slogan "Everyone can leave the world a better place".
Remember a Charity said the campaign, fronted by former newsreader Michael Buerk, increased awareness of the group among adults older than 45 from 38 per cent to 49 per cent.