The Self-Evaluation and Social Support Schedule (SESS), an interview-based instrument, is described, which aims to give a comprehensive description of a person's social milieu in terms of 'objective' and 'subjective' measures. On the basis of a population survey of 400 largely working-class women, a tentative causal model is developed which relates both the quality of current interpersonal ties and childhood experiences to current negative and positive measures of self-esteem. A major purpose of the exercise is to develop positive and negative indices of the social environment that can be used to elucidate the aetiological role of self-esteem in the development of depression. This is the task of a third paper.