This book is a reference grammar of the Kakataibo language, as spoken along the lower Aguaytía River. Kakataibo is a Pano language, spoken by approximately 3000–3500 people in the Peruvian regions of Huánuco and Ucayali. As we will see in §1.3.3, it is possible to identify five different Kakataibo dialects (one of which is extinct, but was documented by Tessman 1930 under the name ).