The regulatory emigration hypothesis was tested experimentally using the crayfish Orconectes causeyi Jester. Varying amounts of food and shelter were provided to crayfish in tanks with escape routes. O. causeyi rapidly adjusted its numbers in harmony with available resources through density-dependent emigration. Shelter influenced the distribution and abundance of O. causeyi most. Response to food occurred but less and took longer than the response to shelter. The small amount of variance between numbers of crayfish that emigrated during both short-term and long-term replicate tests strongly supports the regulatory emigration hypothesis.