This paper serves to review and integrate social exchange and organisational justice theory with regard to the employment relationship. Social exchange relationships are represented by employees' perceptions of workplace inequity represented by their psychological contract and evaluated using organisational justice rules. Employees have in-role and extra-role behavioural responses and cognitive responses to inequity. Behavioural and cognitive responses are moderated by the employee's perceptions of organisational justice. Much employee performance, commitment, engagement, retention and turnover may be explained by this comprehensive model.