Making some fundamental innovations in Word Grammar theory, the thesis explores the nature of syntax (focusing on English) in the areas of (I) relationships between word order and surface constituency, and grammatical relations, (II) the syntax-morphology interface. (I) Dependency and surface phrase structure ('skeletal trees') get defined; mediating between them is s-dependency, essentially a relation of linear precedence but also crucially involved in (among much else) determining extractability and landing sites for extraction, and defining subordination (demonstrated on prepositional passives). A range of constructions where phrases are in some sense 'many-headed' are examined. A relation 'Proxy' is motivated for: relative and interroga...