This monograph reviews a wide range of research literature on the diffusion and adoption of innovations in agricultural production technology in the developing countries, with particular emphasis on the practice of using commercially purchased, inorganic fertilizer as a source of plant nutrients. It is intended that the report's documentation of agronomic, economic, and social factors constraining expanded use of fertilizer in developing countries will provide guidelines for individuals and organizations charged with the responsibility for devising and implementing policies, programs, and projects to promote and facilitate expanded fertilizer use. The review is organized into eight chapters. Chapter 1 provides an introduction to the study. Chapters 2-5 review and assess not only the empirical findings from previous studies on the diffusion of innovations in agricultural production technology in the developing countries, but also the research approaches used in these studies. Chapter 6 summarizes the empirical findings that emerge from the literature reviewed in the preceding chapters, while Chapter 7 outlines some of the key ways in which these findings are relevant to the design of policies and programs aimed at accelerating the rate of diffusion of fertilizer use in developing countries. Finally, Chapter 8 provides a general assessment of the research approaches reviewed. It also lists some of the principal areas in which research is needed to improve understanding of the ways in which constraints impede and delay the diffusion and adoption of fertilizer use in developing countries. An extensive bibliography is included in the document. (KC)