The book is primarily focused on natural plant (lignocellulosic) fibers as sustainable reinforcement material for green composites. It begins with a brief introduction to common plant-based reinforcements, their extraction techniques, the structure of plant fibers, and describes novel fibers extracted from fruit, seeds, leaf, bast, and agricultural waste. The book then focuses on the application of these fibers as reinforcements for composite materials, covering reinforcement and composite fabrication techniques, as well as their performance evaluation. Overall, the book provides a unique and comprehensive look at lignocellulosic fibers for use in green composites, appealing to both researchers in the area of sustainable materials and industry professionals and entrepreneurs interested in their utilization in value-added composite products.