<p>The performance of the composite varies as a function of the volumetric fraction of reinforcement, the interfacial strength between the fibre and the matrix, the sequential arrangement of fibre stacks, and the directional orientation of fibres. Mechanical testing is performed to get insight into the performance of the composite under tension, impact, bending, etc. Early developments of composites led to the use of ceramic, metallic and polymeric matrices with synthetic fibres as reinforcement. Recent developments have focused on reinforcement that is obtained from nature (plants, minerals, and animals), as they are not only environmentally friendly, but also have a wide scope of analysis through variation in volumetric content of fibres, their orientation, fibre treatment, and stacking arrangement that would give optimized properties. Natural fibre-based composites are nowadays explored for solid waste management, reduced greenhouse effect and recyclability, so as to achieve end of service life utility. The hybridization of fibres further broadens the scenario for the enhancement of mechanical performance analysis of composites with a desired combination of reinforcements that otherwise could not have been achieved in a single fibre. This article concentrates on hybrid composites with specific discussions on the fibre–matrix interface and the role of interfacial adhesion on the mechanical response of hybrid composites. It focuses on fibre treatment effects that promote amplification of mechanical strength.</p>