The dream has come true for biologists in California who want to work with human embryonic stem cells. A large sum of money ($300 million annually for ten years), the promise of new buildings, a state research institute dedicated to the field and a constitutional guarantee of the right to do the work all sailed through in a referendum last week (see page 135).

The passage of Proposition 71, as the measure is called, reflects the faith of the public in science's potential to make life better. The infrastructure it creates will make California one of the most suitable places in the world for pushing the frontiers of human embryonic stem-cell research. We have signalled a need for caution (see Nature 431, 723; 200410.1038/431723a), because Proposition 71 is an unusual experiment in science funding. Nevertheless, many leading researchers have staked their reputations on its success and deserve credit for their hard work to pass the measure.

There is still a chance that President George Bush and his allies in Congress who oppose the research could undermine Proposition 71 with a federal ban on essential techniques such as ‘therapeutic cloning’. But such a bill has failed twice in the Senate already, and the chances that it would pass are less now that some prominent conservatives have lent their support to embryonic stem-cell research.

Researchers outside California will be right to worry that Proposition 71 could weaken embryonic stem-cell research elsewhere. Strong privately funded US research centres exist outside California — at the University of Wisconsin and Harvard, for instance — but young researchers especially are likely to feel the pull westwards, and even senior people may find it hard to pass up the lure of new cash and more lab space.

Current limitations on federal funding for the research mean that there are relatively few groups already working with human embryonic stem-cell lines in California. The administrators of the institute, who are to be appointed within 40 days, and the grant review board they will nominate, must avoid merely enhancing existing programmes and recognize the potential of newcomers to stimulate innovation. At the same time, Californian stem-cell research should strive where possible to grow from within.