In Chap. 5 , we learned to apply general engineering principles to normalize away the impacts of bone mass, and measure estimated material-level mechanical properties. This allowed us to examine the mechanical properties of bone when it is fractured by a load sufficient to exceed the failure stress of the material. This type of analysis is useful and important, but there are two principal ways in which structures may fail more gradually: creep and fatigue. In these situations, stresses are applied at levels below the ultimate stress/strength of the material, and the accrual of damage ultimately leads to failure. This chapter will cover the theory behind these loading modalities and their applications in bone.