The William and Flora Hewlett Foundation is one of the biggest private foundations in the US. Based in California, it has been making grants since 1966. Most of its work is in education and international development; it addresses environmental and population issues such as helping women control when they have children and preventing unwanted pregnancies.
In recent years, the foundation has moved towards a global remit, working more with government departments such as the UK's Department for International Development.
"We're never going to be on the same scale as a government agency so we look for areas such as research, rather than direct assistance, as well as agencies such as Oxfam International," says Paul Brest, president of the foundation.
"On climate issues we are actively looking for partners we can work with in the UK. The UK, the US, China and India are the huge emitters, and if we can't get them under control we can't succeed."
Brest, who has been in the role for eight years, has noticed a number of recent trends in grant-making and believes evaluation is now taken more seriously.
"There's certainly much more talk about evaluation and measuring impact than when I started in the sector eight years ago," he says. "Yes, there's more talk than action, but I think that's a good start."
He has also seen the rise of the new philanthropists, which he says has led to new types of grant-making.
Brest says the Bill and Melinda Gates Foundation, established by the Microsoft founder and his wife, is in a class of its own. "The grant-making is smart and focused," he says. "It works in partnership with others and it cares about evaluation, which I admire.
"A lot of the other new wealth remains speculative. There are interesting ideas about and there is an increasing amount of interest in combining for-profit investments with grants, but we'll see how it plays out."
All in all, Brest says he has enjoyed the last eight years and describes his job as "wonderful".
"When I hear anyone complain about being the president of a US foundation, I think 'they don't know what the real world is like'," he says. "The opportunity not just to improve society but your own practices is so great."