A comprehensive theory of selective opacity effects-configurations in which syntactic domains are opaque to some processes but transparent to others-within a Minimalist framework.In this book, Stefan Keine investigates in detail "e;selective opacity"e;- configurations in which syntactic domains are opaque to some processes but transparent to others-and develops a comprehensive theory of these syntactic configurations within a contemporary Minimalist framework. Although such configurations have traditionally been analyzed in terms of restrictions on possible sequences of movement steps, Keine finds that analogous restrictions govern long-distance dependencies that do not involve movement. He argues that the phenomenon is more widespread and abstract than previously assumed. He proposes a new approach to such effects, according to which probes that initiate the operation Agree are subject to "e;horizons,"e; which terminate their searches. Selective opacity effects raise important questions about the nature of locality in natural language, the representation of movement-type asymmetries, correlations between clause structure and locality, and possible interactions between syntactic dependencies. With a focus on in-depth case studies of Hindi-Urdu and German, Keine offers detailed investigations of movement dependencies, long-distance agreement, wh-dependencies, the A/A' distinction, restructuring, freezing effects, successive cyclicity, and phase theory. Keine's account offers a thorough understanding of selective opacity and the systematic overarching generalizations to which it is subject.