Carnivores of Maranhão is a kind of “umbrella project” that encompasses several aspects relevant to the ecology and conservation of carnivorous mammals in Maranhão and the adjacent areas of Pará and Piauí (mid-north of Brazil). These include distribution and habitat use, status and other aspects of species conservation. The project recently finished with an analysis of the jaguar (Panthera onca) and bush dog (Speothos venaticus) and is conducting a similar evaluation of Neotropical and Giant otters. We found interesting results for several species, even to change the existing concepts. This umbrella project also includes various aspects of the ecology of several carnivores.