Stress at work has to be described by a basic concept of stress which understands the relations between work conditions and personal characteristics as a process of mutual influence. Work situations as "potential" stressors become significant when the workers feel under- or overcharged and consider the situation as not transparent, not predictable and not controllable. Intrapsychic perceptional and evaluative processes and competence of action determine the manner of coping with threatening work situations. On the other hand, work conditions not only function as stresors but also as a determinant factor for the acquisition of coping competence. By this fact, job design becomes important not only for the reduction or prevention of actual stress but also for the acquisition of coping competence for future demands.