Sustainability, industrial ecology, eco-efficiency and green chemistry are guiding the development of next generation of materials, products and processes. Biocomposites (natural/bio-fiber composites) and nanobiocomposites (nanofiller reinforced bioresin/biocomposites) are emerging as a viable alternative to glass fiber reinforced composites especially in automotive, packaging and building product applications. The combination of cellulosic biofibers like kenaf, industrial hemp, flax, jute, henequen, pineapple leaf fiber(PALF), sisal and wood fibers as well as the organic and inorganic nanoreinfocements such as cellulolose nanowhisker, nanoclay, nanosilica and nanoalumina etc. with polymer matrices from both non-renewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention i.e. biofiber/nanoreinforcement-matrix adhesion and novel processing. Most works on the development of traditional composite materials considered fiber-matrix adhesion to be a necessary condition to ensure good composite properties. The recent developments on use of well-known physical and chemical surface treatments on properties of biocomposites and nanobiocomposites will be highlighted in this presentation. Hybrid biocomposites containing combinations of cellulosic fiber along with very small volume of glass fibers and/or nanoreinforcents with optimum surface treatments as well as novel processing conditions can lead novel structural materials of much commercial success. This research is financially supported by NSF-DMI 2004 award number 0400296 for the project “PREMISE II: Design and Engineering of Green Composites from Biofibers and Bioplastics”.