The objective of this research is to achieve direct chemical bonding of structurally strong implant materials with hard and soft tissues. This objective has been achieved through the development of a series of surface-active bioglasses and bioglass-ceramics. A controlled release of Ca, P, and Na ions from the surface of the materials produces an alkaline pH and nutrient constituents at a time when the body can incorporate the ions into newly formed tissues. Optical and electron microscopy of in-vivo implants in rat femurs and muscles show the development of stable chemically bonded physiological interfaces after 6 weeks. Microstructure and crystallinity of the materials do not influence the bonding achieved. Mechanical measurements of the bond strength in bone show that the bone fractures before the interface does. In-vitro studies of protein epitaxy, hydroxyapatite crystallization, and solubility kinetics correlate with the proposed interfacial bonding theory.