Users on an XP team help write and pick stories and make domain decisions during development. Users are most valuable if they have broad knowledge and experience with systems similar to the one being built and if they have strong relationships with the larger user community that will use the system once it is fully deployed. Users need to keep in mind that they are speaking for an entire community. They should defer decisions with broad consequences until they can talk with others in that community, giving the team other stories to work on in the meantime.