Delamination is one of the most common types of damage in laminated fibre-reinforced composites due to their relatively weak interlaminar strengths. The delamination failure mode is particularly important for the structural integrity of composite structures because it is difficult to detect during inspection. A design tool for the analysis of delamination in laminated composites is presented in this book. A new model is formulated in the context of Damage Mechanics by means of the Cohesive Zone Model concept and can be used either to simulate quasi-static or fatigue loading in laminated composites. The model developed can be used to perform either strength or damage-tolerance verification of new components, and can be used to assess the necessity to repair or replace in-service components.