The concepts of need and needs are pervasive in everyday discourse, public policy, especially social policy (see e.g. Witkin & Altschuld 1995, Brazelton & Greenspan 2000), management and marketing (see e.g. Jackson et al. 2004), and international policy areas such as humanitarian aid and the Millennium Development Goals. They have a long history in humanistic economics (Lutz & Lux 1988) and parts of welfare economics (e.g. Pigou 1920), even if sometimes different words were used (Amartya Sen, interviewed in Weiss et al., 2005: 240). Needs language essays some central functions – first, to make analyses of motivation richer and more realistic, extending our explanatory repertoire beyond ‘economic man’; second, to analyse instrumental roles and connections; and third to help structure and humanise policy prioritisation, and extend our evaluative repertoire beyond conventional economic measures such as per capita income. In all this, needs language attempts a communicative function too: to support the explanatory and normative work with frames that are simple enough yet robust enough to be usable, yet not too misleading, in routine professional and political discourse. Needs language is hard to order, because of how widespread and varied these roles are. Pervasive use has been frequently accompanied by casualness and obscurity. Added to currents opposed to any notion of publicly determined priorities rather than only market determined priorities, this has led to frequent opposition to the category of ‘needs’ in economics. Work in the past generation strengthened the structures of needs language, reinforcing it as a central medium in policy and administration and connecting it to the languages of human rights and well-being. This entry looks at the variety and nature of needs concepts, and at their relationship to research on human well-being and to ideas of human rights.