Primary health care has a new tool with which to improve its effectiveness, its efficiency, and its decisions about national and local priorities: the accurate measurement of the chances of occurrence of a future event of health or illness. Human and other resources should go where the need is greatest, and assessment of the risk of future illness, accident, or death is a useful short cut to the measurement of that need--both for individuals and for communities. This book presents suggestions for the use of risk information in health care for mothers and children. Most of these suggestions still have to be tested in populations of village communities, migrants, nomads, and the inhabitants of urban slums. In these areas, mothers and children are at their most vulnerable and health systems research is the most difficult. Because of the need for sophisticated epidemiology and statistics in testing the usefulness of the new risk information, general and technical training programs are being developed for health systems research and the use of risk data in general. The present discussion introduces both types of programs. Appendices include discussions of target health problem selection and risk measurement, and an annotated bibliography listing 22 references. (CB)