Abstract: A method is described for performing distributed genetic programming using a server and a plurality of client machines which are connected together by a computer network such as the Internet. The genetic programming seeks to optimise a population of individuals against one or more predetermined fitness criteria. The method includes downloading instructions for performing a fitness evaluation on an individual from the server to the client machines; distributing individuals from the population of individuals from the server across the plurality of client machines; and evaluating the fitness of the distributed individuals at the client machines by using the downloaded instructions. Those individuals which have the best fitness are preferentially selected for breeding to produce the next generation of individuals. This breeding is preferably also performed on the client machines.