This volume highlights some recent developments on plants used widely as botanical dietary supplements and herbal medicines, especially in of knowledge of the chemical types and diverse biological activities of their constituents, as well as laboratory approaches for their quality control and taxonomic identification. In the first chapter, the biologically active secondary metabolites are described of selected botanicals that have a wide current use in the United States, with recent information provided also on their in vitro and in vivo biological activities. The second chapter constitutes an updated survey of the different chromatographic, spectroscopic, and metabolomics techniques that can be utilized for the quality control of botanical products. The penultimate chapter covers different nomenclatural systems that are of use for the taxonomic identification of source plants used in botanical products. Finally, deoxyribonucleic acid molecular barcoding techniques for the identification for plants used as dietary supplements are covered.