The PILDAT report on Performance of the Parliamentary Committees of Defence and the National Security during the first 3 years of the 13th National Assembly of Pakistan is a first attempt of its kind in Pakistan by an independent institution and prepared in the backdrop of principle of Parliamentary oversight of security sector. The report covers a period of three years, i.e., from March 15 2008 to March 15 2011 examining closely the publicly-available data on the work of the National Assembly and Senate Standing Committees on Defence and the Parliamentary Committee on National Security the three committees charged with the responsibility of dealing with subjects relating to defence and national security. PILDAT is mindful of the fact that the democratic institutions like the Parliament and Parliamentary committees have not developed over the years due to repeated military intervention and long spells of autocratic or semi-autocratic regimes led by military. The report therefore is meant to assist the committees in their oversight functions. The objective of the report is not to offer a critique of the work of these committees but to analyse the performance in the backdrop of peculiar security needs of Pakistan and the role Parliament is playing in respect to defining and influencing policy and principles of national security. Furthermore, in the backdrop of specific civil-military equation in Pakistan, the purpose of the report is to examine the exercise of available powers of the Parliament by these committees with regards to Parliamentary oversight of defence and security sector a question that has gained special significance after the killing of Osama Bin Laden at the sovereign soil of Pakistan by the US troops. The report is part of PILDAT’s larger focus on improving civil-military relations in Pakistan in the light of the Constitution of Pakistan and assisting Parliament and its committees in undertaking well-researched, objective and non-partisan oversight of defence and security sector alongside other fields in the executive branch.