This paper reviews recent research into the penetration and perforation of plates and cylinders by free-flying projectiles travelling at sub-ordnance velocities. It is shown that over the last few years there has been a significant amount of experimental research into a wide range of projectile-target configurations. Although most of this research has been concerned with the normal impact of monolithic metallic plates by non-deformable projectiles, valuable work has also been carried out on non-normal impact, impact by deformable projectiles, impact of non-homogeneous metallic and non-metallic targets (including laminated targets) and impact of pipes and tubes. Recent analytical developments that enable the important characteristics of the penetration and perforation process to be modelled are reviewed. These include models that predict local deformations and failure, global deformations or both. It is shown that for some impact situations fairly simple analytical models are capable of predicting target response reasonably accurately, but for others, particularly when both local and global mechanisms contribute significantly to overall target response, more complicated models are required. The development of numerical codes that predict target response to projectile impact is briefly reviewed and the capabilities and limitations of current codes are discussed. The review also includes a section on the impact of soils and reinforced concrete structures.