Poultry farming as a means of profit can be made successful only by maintaining the most vigorous and sustained campaign against disease. The aim of the poultry rearer should be to stamp out disease by preventive measures. Practical experience proves the inefficiency of many so-called cures, and points to the urgency of poultry-men endeavoring to understand more thor- oughly the causes of the ailments to which domestic fowls are liable. My aim is to put a concise handbook into the hands of poultry rearers, who should thus be assisted in determining the various diseases and in taking the precautionary steps important in preventing the introduction and spread of contagious diseases. No effort is made to elaborate the scientific side of the subject. Those desirous of obtaining full information about the types of organisms that have been proved to be the specific causes of, or to be invariably associated with, particular disorders, may do so with profit by obtaining fuller works on the subject. Many scientific workers are devoting their time to the problem of combating diseases among poultry, and assistance is willingly given by officers of the experiment stations to farmers who desire to identify any disease causing loss in their flocks. The practical poultryman will recognize the fact that measures for the control of disease cannot be limited to sanitation and the treatment of sick birds, but, in reality, include such important matters as the selection of healthy stock, intelligent feeding, proper housing, and other details essential to the successful management of poultry.