Events that follow binding of the first host ion to an implant’s surface are dictated by reactions not well understood for any biomaterial or device. Understanding these events is the purpose of the Biomaterials-Tissue Interaction Interest Group. Only through such understanding can one definitively answer such questions as: “Why did it fail?” and “What led to its success that we can apply to future devices?” These answers will come from such fields as physiology, immunology, pathology, biomechanics and material science. They will apply to the subjects of every other SIG in the Society. All those interested in the mechanisms of host-implant interaction are welcome to join our quest.