The NaturalProofs Dataset is a multi-domain corpus for studying mathematical reasoning in natural language. NaturalProofs consists of roughly 30,000 theorem statements and proofs, 15,000 definitions, and 2,000 additional pages (e.g. axioms, corollaries), written in natural mathematical language. NaturalProofs contains broad-coverage data from ProofWiki, deep-coverage data from the Stacks project, and low-resource data from mathematics textbooks. NaturalProofs unifies these sources in a common schema and is made publicly available as a resource to drive progress on tasks involving informal mathematics. Please see the description in [Welleck et al 2021], and its corresponding GitHub repository for more details.