Despite Sri Lanka having progressed and achieved success in overall health indicators, child under-nutrition still remains a major public health concern in the country. Statistics of Low Birth Weights, chronic under nutrition (stunting), acute under nutrition (wasting) and levels of children underweight reflect unacceptable rates. As part of its strategy to tackle the problem of under nutrition, in 1990, the UNICEF developed a conceptual framework that recognized the causes of under nutrition as having a multi-sectoral base. Through a re-analysis of existing data in Sri Lanka, this framework acts as a guide to assess the causes of child under nutrition and helps identifying the most appropriate mixture of actions. The risk factors are classified as basic, underlying and immediate causes. These findings are the key to implement evidence based targeted interventions to improve child under nutrition in the country.