After explicit phrase structure rules were abandoned in government–binding theory, some account of the distribution of adverbials became necessary. This review surveys two current theories. The first, often called the scopal theory, posits that the main factor is semantics: In general, adverbials can appear wherever they cause no violation of semantic well-formedness. Purely syntactic and morphological factors play a role, but it is a relatively minor one. Though the scopal theory predicts a significant range of adverbial distribution correctly, much of its underlying semantic analysis remains to be developed in explicit terms. The second theory discussed in this review, the cartographic theory, takes syntax as central, proposing that adverbials are individually licensed by dedicated functional heads, arranged in a rigid hierarchy by Universal Grammar. This approach has some empirical successes but also a number of problems; thus, the scopal theory is more likely to represent the right direction.