The background papers have been conducted to facilitate the formulation of the National Social Security Strategy (NSSS) of Bangladesh in 2015. These background papers not only will add to the existing knowledge on social security issues in Bangladesh but also will delineate the rationale behind the adoption of NSSS in the country. The compiled work titled Exploring the Evidence, depicts the historical endeavour of Bangladesh to address the issues of social protection. The papers, based on the evidence regarding poverty situation and vulnerability of the poor class, sum up the concepts and theories defining the erstwhile social security system of Bangladesh prescribing a clear outline of a new system of social protection to be adopted. The collection will be a useful reference material to the policymakers, development partners, academics and researchers in their future work concerning operation of social security programmes in Bangladesh.