Linguistic illusions are cases where we systematically misunderstand, misinterpret, or fail to notice anomalies in the linguistic input, despite our competencies. Revealing fresh insights into how the mind represents and processes language, this book provides a comprehensive overview of research on this phenomenon, with a focus on agreement attraction, the most widely studied linguistic illusion. Integrating experimental, computational, and formal methods, it shows how the systematic study of linguistic illusions offers new insights into the cognitive architecture of language and language processing mechanisms. It synthesizes past findings and proposals, offers new experimental and computational data, and identifies directions for future research, helping readers navigate the rapidly growing body of research and conflicting findings. With clear explanations and cross-disciplinary appeal, it is an invaluable guide for both seasoned researchers, and newcomers seeking to deepen their understanding of language processing, making it a vital resource for advancing the field.