This chapter constructs a framework for understanding authenticity in film and television adaptations of H.P. Lovecraft’s fiction. The framework is based on two interrelated qualities of Lovecraft’s stories. First, how Lovecraft’s protagonists seek to authenticate their encounters with unknown horrors through their written accounts. Second, the aesthetic criteria that Lovecraft sees as marking the authentic weird tale. Central to both is Lovecraft’s prose style, which combines detailed descriptions of characters’ perception of monsters with an ineffable sense of terror and assertion that the horrors cannot be described, thus situating them in the realm of the conceptual. Kamilla Elliott’s (2003) dismantling of the binary that is often upheld in adaptation studies whereby words are deemed conceptual and images perceptual provides a foundation for examining the ways in which screen adaptations of Lovecraft’s writing can adapt both its perceptual and conceptual qualities. I enact this exploration by analysing two film adaptations of Lovecraft’s stories—The Call of Cthulhu (Andrew Leman, 2005) and Color Out of Space (Richard Stanley, 2019)—and two television adaptations of his story “Pickman’s Model” from the anthology shows Night Gallery (NBC, 1969–1973) and Guillermo del Toro’s Cabinet of Curiosities (Netflix, 2022). My analysis is attuned to distinct ways that each adaption utilises the specificities of film and television, thereby demonstrating the applications of a framework based on authenticity and its ability to read across different approaches to Lovecraft adaptation and production contexts.