The little-known Pale-mandibled Araçari is endemic to wet forests of western Ecuador. I quantified population density, feeding ecology, reproductive biology, and vocalizations. Population density in the study area was one group (nine individuals) per 333 ha. They were observed to consume fruits of 34 species of plants, of which Lauraceae and Palmae were the most important. Pale-mandibled Araçaris fed their young fruits from at least eight species of plants, insects from five orders, adult and nestling birds, and bird eggs. Nests were made in cavities within live trees, typically Carapa guianensis, and clutches consisted of at least two eggs. At one nest, incubation lasted approximately 17 d. Nestling care in one nest lasted at least 44 d, and was shared by the female, the male and at least one helper. Pale-mandibled Aracaris roosted in groups of up to seven individuals. Ninety-five percent of primary forest in the range of this species had been cut by 1988, and less than 1% of its original habitat lies within protected areas.