Adolescent girls have been recognised as a key group requiring nutritional support. This study compares the findings of Fill the Nutrient Gap (FNG) analyses in El Salvador, Ghana, Madagascar and Lao PDR, on the cost of meeting the nutrient needs of adolescent girls compared to other household members and investigates the drivers of these results. In all four countries, the cost of meeting the nutrient intake recommendations of the adolescent girl was one of the highest among all household members. In contexts with fewer affordable nutrient dense foods available, in particular iron-rich foods, the cost the diet of an adolescent girl was considerably higher than that of a boy of the same age, demonstrating the vulnerability of this group.