The title of any monograph must necessarily be a compromise between brevity and precision, and the needs of this compromise are particularly pressing in a newly emerging area of scientific interest, one that is not only inter- or bidisciplinary, but tridisciplinary, involving as it does psychology, pharmacology, and genetics. The temptation to call this work "psychophar­ macogenetics" -tout court, if the phrase can be applied to so polysyllabic a construction-was removed by the timely appearance of the book under that title edited by Eleftheriou (1975b). Accordingly, something less novel has been chosen. It might be thought to promise more than it delivers and to delineate a wider field than it covers, but I have sought to add a corrective degree of precision in the subtitle which accurately defines what is intended even at the cost of further polysyllabification. The survey of a disparate field of this kind entrains difficulties that go beyond what to call it. The claims of the parent disciplines for methodological supremacy are strong and difficult to resist. What I have done is to seek to impose a degree of coherence on the chosen area by always inquiring to what extent a particular methodology, derived from one part of one of them only, can be applied to the whole.