This entry discusses the problem of the cognitive penetrability of perception. In section “Background and Context: The Putative CP and Theory-Ladenness of Perception,” the parameters of the problem of the CP of perception are analyzed, starting by the existing definitions of CP. Then, what one intends by “perception” and the types of interaction between perception and cognition are discussed. In section “Debates and Challenges,” the state of the debate on CP is discussed. First, the main factors that determine whether come cognitive influence constitutes a case of CP are analyzed. Second, concentrating on the modern discussion on whether recent neuroscientific evidence supports the CP or the CI of perception in general and of early vision in particular, the relevant empirical evidence is assessed. Finally, in section “Possibilities,” the prospects of the debate on the CP of perception are discussed, in view, first, of recent efforts, which are based on neuroscience, to explore the interaction between perception in general and cognition (Vetter et al., 2024). The debate, second, has been enriched by the development of the relatively recent view of perception as a Bayesian predicative process.