'Stress' is a psychological and physical reaction to those demands of the environment which exceed the individual's ability to adjust to them. The severity and length of this reaction can take the forms of various ailments (e.g., heart diseases, diabetes), or of alcohol abuse and family problems. Such reactions vary with the individual's ability to cope with the situation perceived as stressful. Many aspects of police work are seen as causing stress. The empirical evidence that police work is more stressful than that of other occupations is inconsistent. However, all the studies leave no doubt that police work is relatively stressful and that the potential consequences affect society more than stress from most other occupational groups. Studies of police stress should shift away from trying to establish whether police suffer more or less stress than others and should concentrate on the sources and consequences of police stress and their prevention and alleviation. To this end, the findings of major studies of 2,200 police officers in the United States, and of 5,000 police officers in Australia are being currently analyzed. Statistical data, a diagramatic model illustrating the relationship of stress and strain, and over 40 references are included.