The study of sign languages provides a unique perspective on the human capacity for language and enables researchers to distinguish universal properties of language and its neural implementation from modality-specific adaptations. This course introduces the psycho- and neurolinguistics of sign languages, using data collected in collaboration with deaf signers and signing communities to reconsider foundational theories developed primarily from spoken languages. Through the lens of sign language linguistics and neurocognitive data, students will examine language acquisition, language comprehension and production, hemispheric specialization, neural plasticity, iconicity, spatial language, and the relation between linguistic signs, co-speech gesture, and nonlinguistic action. Particular attention will be paid to the ethical considerations of research with linguistic and cultural minorities as well as to unequal access to a sign language, including what delayed first-language acquisition reveals about sensitive periods, and brain development. We will compare converging evidence from behavioral experiments (e.g., reaction-time and eye tracking studies), electroencephalography and evoked potentials (EEG/ERP), neuropsychology (i.e., lesion studies), as well as functional, structural, and diffusion magnetic resonance imaging (fMRI/sMRI/dMRI), which all strongly suggests that the human brain is specialized for processing language independent of the modality of language use (e.g., sign, speech, or tactile sign.). Hands-on activities will ask students to critique influential studies, identify confounds in cross-modal comparisons, formulate testable hypotheses, and design inclusive as well as theoretically well-motivated experiments. By bringing linguistic theory into dialogue with psychology and cognitive neuroscience, the course addresses a central question: How can seemingly radically different perceptual and articulatory systems interact with a universal linguistic system while, at the same time, shaping processing strategies and neural organization? The course is intended for advanced undergraduates and graduate students. No prior knowledge of a sign language or neuroimaging is required; but prior basic training in linguistics is strongly recommended.