Children may be regarded by their caretakers as "difficult" or hard to manage for a variety of reasons including physical defects, clumsiness, and problems in learning. Difficult temperament and other temperament risk factors are described as those normal behavioral style characteristics predisposing the child to a poor fit with the environment, to excessiely stressful interactions, and to secondary clinical problems. These risk factors in the child tend to be regarded by parents as hard to manage but may not be. Clinical outcome depends largely on the response of the milieu. Temperament risk factors are clinically significant because of both the likelihood of problems in routine management and the predisposition to secondary clinical disorders such as behavioral abnormalities or poor academic performance. Available techniques for measurement of temperament are inexact but adequate. Difficult temperament should be distinguished in particular from reactive behavior problems because management of difficult temperament should entail the encouragement of parental adaptation rather than the discipline, behavior modification, or psychotherapy more appropriate for behavior problems. Principles of management of difficult temperament are: recognition of the problem, reorganization of the management, and relief for the parents.