Foreword

work was supported by a grant to the IUSSP from the Bill & Melinda Gates Foundation.The charge to the panel was to assemble and synthesize theories of contraceptive change that have been developed by scholars over the past five decades, with specific reference to low-and middle-income countries (LMICs).The background, and motivation, for this effort was the substantial increase in the use of contraception, especially "modern" methods, in the decades since 1960.We term this "contraceptive transition," which the panel defined as the historical process in which contraceptive prevalence rises from low levels-around 10%-to about 60% among women of reproductive age.This shift represents a transition from a rare practice to one adopted by the majority of women of reproductive age.Note that this is an aggregate-level definition; the panel's brief was to interrogate theory that strives to explain societal trends, not differentials among women.This rather elementary definition was deliberatively chosen to be encompassing of the existing scholarship on contraception; the panel feared that more complex and restrictive definitions would have the unintended consequence of excluding valuable historical experience.It should be added that while developing an understanding of the determinants of trends in the prevalence of contraception is a demanding endeavor, the panel has also recognized the growing demand for multidimensional definitions of contraception that recognize factors beyond prevalence alone (e.g.women's reproductive agency/autonomy).