Imagine, if you will, that you have made billions of dollars from Internet stocks and you wish to leave your estate to relatives. Your money is locked up in a safe whose combination only you know. You don’t want to give the combination to each of your seven children because they are less than trustworthy. You would like to divide it among them in such a way that three of them have to get together to reconstruct the real combination. That way, someone who wants some of the inheritance must somehow cooperate with two other children. In this chapter we show how to solve this type of problem.