Although cognitive theories of psychopathology are often formulated solely from the point of view of the individual, it is important not to lose sight of the fact that the individual exists in a social environment and that relationships with others are often critical for well-being. It is known that loss, separation, and other disruptions to close relationships, whether these occur early or late in life, are associated with many kinds of psychopathology. Equally, the existence of social support appears to reduce the impact of stressful experiences as diverse as rape and open heart surgery, and good support is associated with a better outcome in patients suffering from disorders such as cancer, multiple sclerosis, and chronic kidney disease. It is common for patients who consult psychologists to have low levels of support, whether because of poor social skills, isolation from others (self-imposed or situationally determined), or because of current difficulties in their intimate relationships or in relationships with people in authority. Many kinds of psychotherapy, whatever the theoretical model underlying them, share a common concern with improving patients' relationships with others, and take particular note of any difficulties that feature in their responses to the therapist's suggestions and interpretations. For these reasons some knowledge of the dynamics of interpersonal relationships is essential for any practising psychologist.