Equity in health and health care have become important priorities for the w
orld. If efforts at achieving equity are to have any basis in evidence conc
erning which strategies are likely to work, a research agenda is necessary,
An adequate research agenda requires a knowledge of what the problem is, a
n understanding of the genesis and correlates of the problem, methods to me
asure these correlates, and rigorous testing of alternative explanations an
d interventions. This article presents a working definition of equity in he
alth and health services, a conceptual framework in which to view the vario
us types of influence on health and distribution of health in populations,
a summary of evidence on the effects of some of these categories, and a res
earch agenda for guiding efforts to improve knowledge on which to base inte
rventions that enhance the attainment of equity. Because of their relative
neglect in the existing literature on equity in health, the special roles o
f political forces and of primary care as a particularly key element of hea
lth services are stressed.