The fatigue behavior of an adhesively bonded joint is of key importance to its long-term structural integrity. However, the complex stress distribution inside a bonded joint does not make it easy to evaluate the fatigue behavior. This chapter discusses the various approaches that have been developed for predicting the fatigue behavior of adhesive bonds, including stress-life methods, damage mechanics, strength and stiffness wearout, fracture mechanics, and damage mechanics. It also covers experimental and numerical techniques and reviews the current understanding of the effect of joint geometry and environment.