We frequently use characterisics of temperament when we describe our patients, be they children or adults. We may say that a particular patient is "difficult" or "easy," perhaps "distractible" or "slow to warm up." Descriptively, the concept of temperament has always had a place in our formulations. In their most recent work, Chess and Thomas have summarized and amplified their work of 30 years with the New York Longitudinal Study, and in doing so they have widened the scope of this concept. That is, temperament may be considered to be far more than a descriptive concept, as they demonstrate clearly. The place of temperament in our theoretical understanding has been elucidated, and its usefulness in understanding the developmental process has been clarified.
The authors are quick to point out that they do not consider temperament a theory of development but rather one attribute of an individual, and one that, when