Developmental ideas and models concerning family life have been disseminated widely around the world where they have become forces for both ideational and behavioral change. In this paper, we examine the ways in which ideas about marriage have been influenced by these ideas of development in Nepal, where, for centuries, young age at marriage, arranged marriage, and polygamy have been common practice, and intercaste marriage and divorce have been virtually non-existent. Using recently collected data from face-to-face surveys and semi-structured interviews, we demonstrate that large fractions of Nepalis now endorse marriage behaviors more similar to those frequently heralded as “modern” or “developed” family behaviors. Our results suggest that preferred age at marriage has risen, tolerance for intercaste marriage, divorce, and the involvement of young people in the choice of their spouse has increased, and polygamy has become increasingly taboo. Cohort replacement, increasing education, media exposure, and urbanization help explain these changes. However, although there has been dramatic change in the attitudes Nepalis have about marriage practices, we do not find complete acceptance of so-called modern family attitudes. Developmental ideas and models of family life have been creatively and selectively integrated into the continuously evolving models of family life in Nepal.