One anaphora (e.g., this is a good one) has been used as a key diagnostic in syntactic analyses of the English noun phrase, and “one‐replacement” has also figured prominently in debates about the learnability of language. However, much of this work has been based on faulty premises, as a few perceptive researchers, including Ray Jackendoff, have made clear. Abandoning the view of anaphoric one (a‐one) as a form of syntactic replacement allows us to take a fresh look at various uses of the word one. In the present work, we investigate its use as a cardinal number (1‐one) in order to better understand its anaphoric use. Like all cardinal numbers, 1‐one can only quantify an individuated entity and provides an indefinite reading by default. Owing to unique combinatoric properties, cardinal numbers defy consistent classification as determiners, quantifiers, adjectives, or nouns. Once the semantics and distribution of cardinal numbers, including 1‐one, are appreciated, many properties of a‐one follow with minimal stipulation. We claim that 1‐one and a‐one are distinct but very closely related lexemes. When 1‐one appears without a noun (e.g., Take one), it is nearly indistinguishable from a‐one (e.g., take one)—the only differences being interpretive (1‐one foregrounds its cardinality while a‐one does not) and prosodic (presence versus absence of primary accent). While we ultimately argue that a family of constructions is required to describe the full range of syntactic contexts in which one appears, the proposed network accounts for properties of a‐one by allowing it to inherit most of its syntactic and interpretive constraints from its historical predecessor, 1‐one.