In recent decades, climbing has gained in popularity in western countries. Outdoor rock climbing affects the biodiversity associated with cliff faces and adjacent habitats. As these habitats host unique species assemblages that are largely undocumented, primarily because they are difficult to access, climbing could threaten populations of species of conservation interest. This literature review: 1) provides a portrait of the biodiversity associated with cliffs, screes and boulders, using North America as a case study; 2) summarizes the current knowledge about the ecological impacts of rock climbing; 3) documents current mitigation measures; 4) identifies knowledge gaps; 5) suggests avenues for research and conservation efforts.