The mechanisms of load transfer in single carbon-fibre/epoxy-resin model composites, are investigated. The composites are subjected to incremental tensile loading and the fibre fragmentation process is continuously monitored. The fibre strain distribution along the fibre fragments is derived through the Raman spectrum of the carbon fibre and its strain dependence. In turn, the interfacial shear stress distribution is evaluated by means of a balance of forces analysis. The effect of fibre surface treatment and fibre modulus upon the stress transfer profiles and the distribution of the interfacial shear stress along the fibre, are also examined. Finally, the importance of parameters, such as, fibre/matrix debonding and interphasial yielding at the vicinity of fibre breaks, is discussed.