Background: There is growing awareness in the field of public health that combatting the double burden of malnutrition requires approaches that address its multi-dimensional origin, rather than focusing primarily on the biomedical domain. Current frameworks of malnutrition like the UNICEF conceptual framework, and the Lancet Series 2013 framework have been instrumental in understanding the determinants of malnutrition and developing appropriate interventions. However, these frameworks fail to explicitly address issues of agency, that is, about being able to pursue one's goal. The capability approach as originally developed by Amartya Sen includes agency in the causal chain. Summary and key Messages: In the past 5 years, the International Union of Nutritional Sciences Task Force "Towards a multi-dimensional index for child growth and development" has developed a capability framework for child growth, and conducted empirical research applying this framework. The working group discussed what would be needed to further develop the approach and explained the added value to international organisations and policy makers. We suggest developing an index of advantage that will be a proxy for a child's agency. We hypothesise that such an index will explain much of the variance in studying inequalities in child nutrition and thus call for action to improve this focal point.