THE work on which this paper is based forms part of a research into the ecology of game birds carried on by the Bureau of Animal Population. This research has been made possible by a grant from Imperial Chemical Industries and by the donations of landowners and others interested in game preservation. Our thanks are due not only to those who have helped financially but to shooting men and keepers in all parts of the country who give facilities for this work on their estates and send us birds for examination. The sorting out and identification of most of the seeds and other plant food was done by E. Arthurs of the Oxford Botanical Department, while the identification and volumetric measurements of insects were carried out by John Ford and E. W. Aubrooke in the Hope Department of Entomology at Oxford. We are greatly indebted to them for this assistance. The present paper deals only with the food of adult wild partridges. Material collected from young partridges is being analysed and the results will be published later. Young birds are classed as adults when killed any time after the opening of the shooting season, September 1st, but a record has been kept of whether the birds examined were young adults or old birds (over 16 months old) except when crops were sent in separately by keepers and others without data. Altogether, 429 adult grey partridges (Perdix perdix) and 29 red-legged partridges (Alectoris rufa) have been examined for food. The crop contents only have been used for this purpose as food found in the gizzard is usually in such a finely divided state as to be almost unrecognizable and certainly of no value for quantitative work. There is no reason to doubt that the crop contents alone form a truly representative sample of the food eaten. As there is no evidence to suggest that some food items pass more quickly than others from the crop