The research is concerned with the interlaminar delamination problem in unidirectional Carbon Fibre Reinforced Plastic (CFRP) laminates under static and fatigue loading. Analytical models backed by experimental techniques are employed to describe the delamination behaviour in 00 interfaces. The problem of a semi-infinite elastic plate loaded along its straight boundary is persued to develop an analytical and realistic Double Cantilever Beam (DCB) Model which accounts for the end deflections associated with deformation beyond a crack tip. Comparisons with the predictions of existing models and with available experimental data show good agreement. The analysis is used to formulate the strain energy release rate (SERR) and the corresponding stress intensity coefficient. This shows excellent agreement with other results from more elaborate methods. The SERR is also formulated for a tapered double cantilever beam and this agrees well with experiment. DCB type specimens were tested in load control where the SERR is measured and compared with theory for, 0* CFRP. Other specimens were tested- in fatigue and the delamination is described for various maximum loads. A Paris type formula is given for predicting crack growth in Oý CFRP. A theoretical analysis is presented for the crack propagation in a layered fibre reinforced plastic strip in compression, in the presence-of a blister. Account is taken of a resin rich layer at the delaminating edge and of an initial deflection* in the blister geometry. Typical design curves are, produced which show the influence of blister length, applied strain and resin stiffness on loads required for delamination. Blistered sandwich specimens were tested in static compression where debonding characteristics are explained. The loads required to initiate delamination are found to compare reasonably well with theory. Similar specimens were tested in constant amplitude fatigue compression loading and delamination behaviour is illustrated.