The thin-spined porcupine, Chaetomys subspinosus, is an endemic mammal of the Atlantic forest of northeastern Brazil. With its population declining, it has been listed as “vulnerable” in the Brazilian Red List. Its National Action Plan, published in 2011, intended to develop awareness projects about the species in local communities, to implement alternative income projects and protein consumption, and to evaluate hunting pressure. This study investigates rural residents' knowledge of the thin-spined porcupine and its uses within two protected areas. We also examine residents' behaviour and perceptions about wildlife conservation. One hundred twenty-five semi-structured interviews were conducted with rural residents of the Una Wildlife Refuge and the Serra do Conduru State Park. Local knowledge was higher among males with lower levels of formal education who were current or past hunters. Negative behaviour occurs among residents in both protected areas. There is a need for greater control of potential threats such as hunting, use of fire and deforestation, which are inconsistent with the existence of protected areas and conservation of the thin-spined porcupine. Information provided by this study can improve and promote actions within the National Action Plan for the conservation of C. subspinosus.