Despite the importance of durable wood bonds, the factors that lead to durability are not well understood, and the internal forces exerted upon the bondline are often overlooked. Durability requires that the bonded assembly resist dimensional changes of wood with fluctuation of wood moisture levels. Both bonding and bond breaking steps need to be understood at cellular and nanoscale, in addition to the larger spatial scales normally examined. With both internal and external forces being significant, interphase and bulk adhesive properties need to be better understood. Systematic studies of the bonding process, the forces upon the bondline, and the locus of failure using different types of adhesives and wood species should improve our ability to design wood adhesives. Modifications of wood surfaces, along with spectroscopic and microscopic analyses, are important tools to understand bond formation and failure.