Some companies are very clear about what they look for in charity partners. For house-building firm Persimmon, one attribute is vital - you have to be a cancer charity.
Since 2000, the company's Building to Beat Cancer campaign has included partnerships with charities including Macmillan Cancer Support, Breast Cancer Care and Dreams Come True.
For 2010 it has chosen Leukaemia & Lymphoma Research. "The charity is celebrating its 50th anniversary this year and blood cancer is something we've not really covered in the past," says Dominic Harman, group communications director at Persimmon.
Leukaemia & Lymphoma Research is no stranger to corporate partnerships. It has worked with DIY retailer Wickes for the past two years and raises £1.5m a year through company fundraising.
However, the cancer charity's corporate partnership with Persimmon began in an unusual way - the charity was asked by a PR agency to pitch for a potential partnership with an unnamed client.
"We didn't actually know which company it was," says Kate White, director of fundraising. "They just said they wanted us to put together a proposal. It was a bit of a mystery, really. But partnerships can happen in all sorts of ways."
One factor that cemented the partnership was Leukaemia & Lymphoma Research's network of regional fundraising teams, which will work with Persimmon's 25 regional head offices.
"Each office has a charity champion or committee," says Harman. "And it works better if there is local support from the charity: people from the charity can support the initiatives offices come up with, but can also have their own ideas."