A special form of failure in impact loaded Fibre-Reinforced Composites (FRP) structures is delamination, in which individual layers of a laminate get separated from one another. In contrast to the continuum mechanically formulated models of damage mechanics, the description of delamination processes is based on concepts of fracture mechanics. Here, delamination initiation is due to interlaminar stresses, whereby the tolerable interlaminar shear stresses can be increased by a simultaneous through thickness compression (TTC). Furthermore, an increase in the critical energy release rate with increasing out-of-plane compressive load is described. Failure to consider the compressive superposition can lead to an overestimation of the delamination failure in impact loaded FRP structures such as three-point bending beams.