From its inception in 1967 to the mid 1980s, the Kenyan national family planning programme suffered from a lack of popular support and confidence within the general population, absence of active local participation at all levels and, above all, the absence of men's involvement in this patriarchal nation. This study measures the effects of men's participation in family planning decisions, and identifies the conditions which would stimulate greater participation by men in family planning decisions. The principal conclusions are that Kenyan men do participate in these decisions, take an interest in planning their families, support family planning and use contraception to achieve their goals. The recent transition to lower fertility is probably due, at least in part, to changes in men's attitudes. In particular, the study shows that lack of communication between husband and wife may be a more important obstacle to the adoption of contraception than men's opposition. Couple communication has the strongest positive influence on current contraceptive use followed by: residence in regions of the country in which conformity to traditional reproductive practices is weaker (Nairobi, Central, and Eastern regions), employment in higher-status occupations, the number of living children, higher levels of education, and the wife's current age. Giving higher priority to the inclusion of men's needs and concerns in the design of family planning programmes should improve their success.