Merge is the structure-building operation in Chomsky's Minimalist Program. In When Arguments Merge, Elise Newman develops a new Merge-based theory of the syntax of argument structure, taking inspiration from wh- questions. She uncovers new connections between disparate empirical phenomena and provides a unified analysis of patterns across many languages and language families, from Mayan to Bantu to Indo-European languages (among others). The result is a syntactic theory with a small inventory of features and categories that can combine in a limited number of ways, capturing the range of argument configurations that we find cross-linguistically in both declarative and interrogative contexts.