This paper presents the lateral stability of a multi-story building subjected to blast load. The basics of blast threats and the of blast wave interaction with buildings are studied here. It is about investigating the lateral stability of a structure modeled using SAP2000. Building is of 6 story is exposed to 100kg, 200kg, 300kg, 400kg and 500kg TNT with 6m stand-off distance. The blast loads are considered using the approaches defined in section 5 of TM5-1300 (UFC 3-340-02) and for the analysis of the dynamic load of the blast, a nonlinear modal analysis is used. The total drift and the inter-story drift are the primary parameters that determine the performance of the structure.