The damage and residual strength of 7075-T6 aluminum panels exposed to caliber 0.50 AP M2 gunfire was found to vary with projectile velocity, impact angle, and target thickness. Maximum damage occurred at low velocities and high impact angles. The strength of thin panels agreed closely with fracture theory because of their predominant cracklike flaws; conversely, the strength of thick panels was close to the material ultimate tensile strength because of the blunt flaw shapes. Damage and residual strength prediction models were developed from the test data for monolithic panels. Alternate design concepts consisting of laminated, planked, and spar cap stiffened panels were investigated. The laminated panels exhibited extensive petaling and star-type cracking and low residual strength. Planked and spar cap stiffened panels provided damage alleviation and crack arrestment with high preload stresses.