Dislocations interact with grain boundaries during yielding, creep, and recrystallization. It will be assumed that the dislocation model for grain boundary structure is valid generally. Consequently, Burgers vectors are conserved and dislocation lines can end only on other dislocations or free surfaces. The following phenomena will be considered : (1) grain boundary dislocation sources, (2) movement of a dislocation in and through a grain boundary dislocation network, (3) transmission of a crystal lattice dislocation across a grain boundary, (4) absorption of dislocations and "core spreading". Energetic and kinetic aspects of each interaction will be discussed and related to experimental observations and grain boundary phenomena