This chapter highlights that researchers interested in assessments need separate, specifically designed tests of language and cognition for deaf sign language users rather than relying on tests designed for users of spoken languages. Tests that are developed specifically for deaf signers and that produce deaf norms are an invaluable tool in both sign language research and clinical practice. When deaf signers are given spoken language-based tests designed to be suitable for hearing populations, there is a potential for linguistic and cultural biases to occur, which can lead to an unreliable assessment. The chapter reviews the language and cognitive assessments that have been developed for deaf children and adults to date, demonstrating examples of good practice. It presents a range of important points to consider when conducting assessments with deaf signers. The chapter concludes with considerations for developing future assessments.