The acoustic signals in Atelopus (Anura: Bufonidae), a Neotropical genus currently composed of 97 species, are poorly known. In this study, we describe for the first time, the advertisement, release, and agonistic calls of Atelopus laetissimus, an endangered species endemic to the Sierra Nevada de Santa Marta, in northern Colombia. The calling behavior of males was associated with reproduction (advertisement calls) and male–male aggression (agonistic and release calls). We also describe, for the first time, calls from female A. laetissimus, constituting the first case of a female's vocalization in the genus, recorded while one male was trying to clasp her. The diverse acoustic signals described here for Atelopus laetissimus suggest the vocal repertoire in the genus Atelopus may be more complex than is currently realized.