The following paper summarises a number of international research projects being undertaken to understand the mechanical properties of natural cellulose fibres and composite materials. In particular the use of novel techniques, such as Raman spectroscopy, synchrotron x-ray and half-fringe photoelastic methods of measuring the physical and micromechanical properties of cellulose fibres is reported. Current single fibre testing procedures are also reviewed with emphasis on the end-use in papermaking. The techniques involved in chemically modifying fibres to improve interfacial adhesion in composites are also reviewed, and the use of novel fibre sources such as bacterial and animal cellulose. It is found that there is overlap in current international research into this area, and that there are complementary approaches and therefore further combining of these may make further progress possible. In particular a need to measure locally the adhesion properties and deformation processes of fibres in composites, with different chemical treatments, ought to be a focus of future research.