Nearly three decades of research support a strong relationship between the complex biological processes that can occur during the first 1,000 days of life and the resulting multiple burdens of malnutrition, including undernutrition (measured as stunting and wasting), overweight and obesity, and micronutrient deficiencies. Although gaps in knowledge remain, the field of nutrition has made commendable progress in identifying which policies, programs, and initiatives “work” to improve nutrition for the most vulnerable groups, particularly among women and children. To date, most evidence on programmatic successes reflect “nutrition-specific” interventions, well described in Chapter 24. Such interventions, highlighted in the 2008 and 2013 Lancet series on undernutrition, reflect 10 interventions in three areas, primarily in the health sector: improving micronutrient uptake through fortification or supplementation, treatment of acute malnutrition, and counseling for breastfeeding and complementary feeding.