Humanity is young: In 2006, over a third (2.2 billion) were under age 18 and almost half were under age 25. In addition, nearly the majority of young people ages 15-24 lives on less than $2 per day, 15 percent are undernourished, and 14.4 percent are unemployed. Although 85 percent of young people live in developing countries, only a fraction of adolescent development and mental health research is focused there. Efforts to shift the emphasis of such research also must engage with the prevailing views in development theory and policy that link human development with socioeconomic development in a "dual development model." A critical cultural analysis of this model reveals both the bases and limitations of its power, and identifies an implicit cultural model of the life course within it. The model mandates society-to-individual (outside-in) investments in health and education that are expected to return reciprocal gains in lifetime productivity that benefit society as a whole (inside-out). The current burden and advantage of this equation are assessed as they bear on young people across the globe. A case is made for lifecourse cultural models as a potent framework for mediating among realities, perceptions, and behaviors at the level of youth, parents, and policies under conditions of rapid culture change. [applied psychiatric anthropology, child development, globalization, education, poverty, culture change] Humanity is young: In 2006, over a third (34 percent, or 2.2 billion) were under age 18 and almost half were under age 25. Moreover, the near majority (47.6 percent) of young people ages 15-24 live in moderate poverty (< $2 per day; 18 percent live in extreme poverty, < $1 per day), 15 percent are undernourished (Curtain 2004), and at least 14.4 percent are unemployed (United Nations 2005). The demographics of youth (defined as persons ages 15-24) reflect tectonic shifts in health, education, and economy. First among these shifts is the success in global efforts to increase infant and child survival that has combined with residual high fertility to yield the largest-ever cohort of young people (Lloyd 2006). Second are the worldwide advances toward universal schooling whereby in 2006 88 percent of primary school aged children and 78 percent of secondary school aged youth were in school even as disparities in accessibility and quality of education increased (Watkins 2008). Third is globalization and urbanization (half the world's population now lives in cities) that have transformed the media, mobility, and economic landscapes for youth, creating youth cultures and opening opportunities but also competition for those opportunities on an unprecedentedly global scale (Kagia 2005). Such massive shifts involve the reorganization of lifecourse cultural models for how to get and live a life, with consequent changes in parent and youth priorities, perceptions, and behaviors. Thus, circumstances