In this paper the author shows that dependency grammars are not only equivalent to structure-free phrase-structure grammars (i.e., equally adequate), but are even more informative: they express both the "is a" relation which phrase-structure grammars express and the "governs" relation which phrase-structure grammars obscure. It is shown that dependency theory with its concept of "governor" succeeds where phrase-structure theory fails and in addition resolves some of the knotty problems left unresolved by other formulations of the concept of "head" in part endocentric terms. The problem of designating a "governor-head" for exocentric constructions of the base component is discussed in terms of selecting among distinctive categories of a structure-free analysis either in phrase structure or dependency terms. As in all transformational grammars, considerations of the results of applying transformations to obtain appropriate structures for derived sentences plays a key role in making the decision. Since a dependency grammar has a unique restatement as a dependency-phrase grammar, the transformation rules defined on its structures can be stated in the phrase-structure form now used (labelled bracketings with variables) or solely in dependency form. The latter eliminates the need for "tree-pruning." (DO)