This chapter begins with an overview of types of health needs assessments that might be undertaken. Then it describes the way that conducting health needs assessment was developed in the United Kingdom. The ways to plan the exercise, assess the structure of a given population, examine the effectiveness of potential interventions and conduct evidence syntheses are described. The complexities of health systems are noted. The relationship between health needs assessment and health economics is then examined. The philosophy of utilitarianism and its influence on health economics is explored. The important relationships between equity and efficiency are considered. The chapter then proceeds to explore the political and philosophical issues linked to health needs assessment particularly health inequalities and the issues of justice, fairness, and equity. This leads to an elaboration of the concept of justice derived from the work of Sen. Using ideas about the importance of human capabilities an argument is developed about the relational approach to understanding justice. The relational as against the individualistic position is found to provide a novel and useful way of describing health need and of attempting to meet that need. It also provides a set of precepts about the ways that services might be configured.