The range of nanomaterial applications has expanded recently from catalysis, electronics, and filtration to therapeutics, diagnostics, agriculture, and food because of unique properties and potentials of different nanoparticles and nanomaterials. Research shows that these exquisite particles can interact with an organism at the cellular, physiological, biochemical, and molecular levels. However, our knowledge of how they affect these changes, selectively or generally, in diverse organism or ecosystems is very limited and far from satisfactory. Data indicate that the biological function largely depends on the shape, size, and surface characteristics of the nanoparticles used besides life cycle stages of an organism. Therefore, this compilation will focus on the body of work carried out by distinguished investigators using diverse nanomaterials and plant and animal species. This book includes specific case studies as well as general review articles highlighting aspects of multilayered interactions, and targets not only research and academic scholars but also the concerned industry and policy makers as well.