Growing industrial and academic interests in the choice of wood fibres as reinforcing fillers in polymer composites; in preference to synthetic fibres; is premised on their excellent mechanical properties, low density, abundance and recyclability. The interface and the functional performance of wood polymer composites (WPCs) can be controlled by appropriate selection of surface modification techniques for wood fibers, materials and processing parameters depending on the specifications for different technological applications. Meanwhile, resultant alterations in the interface and functional performance of WPCs even when the same wood fiber specie is incorporated into different polymeric matrix had been attributed to materials and processing challenges. In this overview, materials and processing challenges (poor bonding and degradation at wood fiber/polymer interface, fiber damage during processing, poor wettability and high moisture absorption) which affect WPCs' interface and functional performance are elucidated with the remedial measures proffered. The appropriateness of various materials and processing parameters for WPC's interface and functional performance is elucidated in an attempt to contribute to the development and promotion of sustainable and competitive potentials of WPCs. (C) 2016 Elsevier B.V. All rights reserved.