Dixon (2004) suggests that the Jarawara language contains no native number terms. This assertion implies that Jarawara is one of the most extreme documented cases of a language with a paucity of number terms (Hammarström 2010), and helped to motivate an investigation into the numerical cognition of its speakers. Investigations among speakers of languages with limited number terminologies have proven useful to cognitive scientists interested in the language-cognition interface (see De Cruz & Pica 2008). For instance, it has been demonstrated that speakers of Pirahã, a numberless Amazonian language, face difficulties when performing basic tasks related to numerical cognition (Gordon 2004, Frank et al. 2008, C. Everett & Madora in press). In order to contrast the numerical cognition of the Jarawara with those of the Pirahã, and in so doing shed light on the interaction between anumeric language and thought, we replicated three of the basic tasks described in the aforementioned studies on Pirahã. Unlike speakers of Pirahã, the seven speakers of Jarawara tested generally performed quite well on the tasks in question. Differences between the two tribes were significant (at pdohave a native cardinal number system, contra Dixon (2004), and that this system can be used for numerosities as large as twenty. In addition to the experimental data presented, this paper includes the most extensive documentation to date of a number system in an Arawá language.