Betalains are a group of plant pigments mainly found in the Caryophyllales order. According to their structure and color, they have been divided into two groups: the betacyaninsBetalainsbetacyanins with red-violet hues and the yellow-orange betaxanthinsBetalainsbetaxanthins. Because of their chemical properties and stability, there is particular interest in the food, cosmetic, and pharmaceutical industries in exploring using betalains as ingredients or pigments to be included in their formulations. The profile of individual betalains can largely vary according to the (plant) source, and, therefore, an increasing amount of literature describing the characteristics of extracts from different plants is now available. This has been possible due to the use of modern analytical methods. In this chapter, besides presenting an overview of the importance of this pigment group, the chemical characteristics, and relevant sources, emphasis is given to the methods employed to analyze these compounds in different plant structures. Most relevant results from reports on betalain analysis are summarized below, and the betalain concentration and profile in the different sources are emphasized, as well as the list of species in which each of the individual compounds has been identified. Finally, information on the bioaccessibility and bioavailability of this interesting group of pigments is given.