Idan Landau offers the first comprehensive account of adjunct control. Extending the framework developed in his earlier book, A Two-Tiered Theory of Control, Landau analyzes ten different types of adjuncts and shows that they fall into two categories: those displaying strict obligatory control (OC) and those alternating between OC and nonobligatory control (NOC). He explains how and why adjuncts shift between OC and NOC, unifying their syntactic, semantic, and pragmatic properties.