Microelectronics, MEMS, photovoltaic, and other devices consist of several thin film layers that are made of dissimilar materials (e.g. metals, low-k dielectrics, polymers, etc.). Such multilayered thin film systems are often prone to cracking and delamination under various loading conditions resulting in premature failure of the devices. For example, sudden catastrophic fracture can occur due to overstresses caused by an unforgiving fabrication process or an overload during operation. Alternatively, cracks can nucleate and grow incrementally over many loading cycles until device failure. Thus, thin film cohesive and interfacial fracture under monotonic and fatigue loading conditions are important reliability concerns for a wide range of applications. Our research in thin film reliability is motivated by (1) developing new experimental test techniques for characterizing thin film fracture and (2) developing analytical and finite element models to study thin film fracture mechanics in various applications.