In this article, a brief account of the psychological sense of stress is referred. Richard Lazarus' transaccional theory is described in detail; his first transaccional cognitive theory and his last cognitive-emotional transaccional theory. Stress is also described from other points of view, such as Grenberg's emotional theory. The new construct Psychofortology is defined and some references about the principal authors are made. Psychotherapeutic possibilities from the different psychological schools mentioned are described.