A wall system protects a building structure from pressure caused by explosive blasts. The wall system includes vertical studs. Outer blast wall panels and inner blast wall panels are secured to the opposing sides of the vertical studs. An upper mounting system is attached to the building structure. An upper mounting system includes a fixed track, a movable mounting track, and an energy absorbing system that flexibly couples the movable mounting track to the fixed track. The upper ends of the vertical studs are attached to movable mounting track. A lower mounting system includes a mounting track that aligns the lower ends of the vertical studs. A respective attachment clip is attached to a lower portion of vertical stud. Each attachment clip is attached to the building structure with an energy absorption pad that resists vertical and lateral movement of lower end of the respective vertical stud.