This entry consists of the conference handbook and transcripts of presentations given at the Fibre-matrix interactions: the physics of reinforcement held 17-18 September 1975 at the University of Sussex. The following presentations are included: Mechanism of reinforcement of polyurethane foam by random short fibres; An examination of tensile failure in partially aligned asbestos/epoxy composites; A theoretical model for tensile behavior of short-fibre composites; Stress concentrations in fibre reinforced materials under transverse loading: the effects of interlayers; Composite micromechanics using finite element methods; The strength and work of fracture composites and their dependence on bond strength; The interaction of reinforcing steels with a concrete matrix; Work-hardening and internal stresses in fibre reinforced composites; Deformation of the Ni3Al-Ni3Nb eutectic composite; A study of failure mechanisms in model glass/resin composites; Direct microscopic observation of failure processes in continuous and discontinuous fibre reinforced thermoplastics; Transition between cohesive and interfacial failure in a laminate; Weak interfaces and their effect on shear, tensile and toughness properties of fibre reinforced resin composites; and, The effects of fibre surface coatings on the mechanical properties of CFRP.