The energy absorption characteristics of E-glass/PP grid stiffened composite panels under high velocity transverse impact loading has been investigated. Experimental results were validated using finite element analysis for both the skin and rib side loading. The results of test and simulations show that grid stiffened composite panels absorb lot of energy under dynamic impact load without catastrophic failure. The panels absorbed more energy when loaded on the skin-side than on the rib-side. The specific energy absorbed under dynamic impact loading was far greater than that for quasi-static loading. Vibration testing was used to analyze the cause of vibratory component in the impact response load-time history. Low velocity induced progressive impact damage in grid stiffened composite plates was also evaluated in a separate study using the vibration response measurement technique. This technique appears to be partially successful in detecting the various levels of induced impact damage in grid stiffened composites.