Abstract Wood is a natural renewable material with unique properties helping mankind to build and develop its communities since the genesis of human on the Earth. Moreover, wood/cellulosic composites provide the opportunity to utilize low-density wood species and agricultural materials that are basically not suitable for structural applications. Although wood is considered irreplaceable, it has some disadvantages narrowing its applications and limiting its service life. These disadvantages mainly include its susceptibility to water and water vapor, biological deteriorating fungi, insects, termites, and marine borers. The present chapter tries to summarize some main areas in which nanotechnology is being used to improve wood and lignocellulosic-based composite panels. Moreover, some new applications and capabilities of this precious natural material are also brought into perspective, areas such as transparent wood, self-cleaning coatings, and smart windows. Though some areas have been thoroughly studied, much potential still exists for further studies and commercialization.