Whether as engravings, drawings, paintings, stencils, or prints, rock art was made on rock surfaces devoid of protective coating. From the moment of its manufacture, it has therefore been subject to a range of environmental conditions and susceptible to a range of environmental impacts, each of which could have changed through time. In this chapter, the authors discuss the biotic, mechanical, and chemical processes that can affect rock art at its interface with the rock matrix and the atmosphere, together known as taphonomy. Given the complex interplay of age, environment, and processes, understanding alteration mechanisms affecting rock art sites and adequately assessing ways of mitigating deterioration require site-specific investigations and complementary scientific fields.