We have taken a look at Chomsky’s phase-based theory of syntax. We noted Chomsky’s suggestion that the computational component of the Language Faculty can only hold limited amounts of syntactic structure in its working memory at any one time, and that clause structure is built up in phases (with phases including CP and transitive vP). At the end of each phase, the domain (i.e. complement of the phase head) undergoes transfer to the phonological and semantic components, with the result that neither the domain nor any constituent it contains are accessible to further syntactic operations from that point on. We saw that intransitive vPs and defective clauses (i.e. clauses which are TPs lacking an extended projection into CP) are not phases, and hence allow A-movement out of their complement, as in structures such as Numerous problems are thought to remain in Utopia. We saw that a phase-based theory of syntax requires us to assume that long-distance A-bar movement (e.g. of wh-expressions) involves movement through intermediate spec-CP positions, since CP is a phase and only constituents at the edge of a phase can undergo subsequent syntactic operations. It was argued that A-bar movement in transitive clauses involves movement through intermediate spec-vP positions. A range of arguments were presented in support of successive cyclic A-bar movement through intermediate spec-CP positions, from structures including preposition stranding in Afrikaans, quantifier-stranding in West Ulster English, wh-copying in adult and child grammars, and wh-marking of complementizers in adult and child grammars. We looked at evidence from have-cliticisation in English, wh-marking of verbs in Chamorro, past-participle agreement in French, mutation in Welsh and multiple wh-questions in Spanish in support of claiming that wh-movement in transitive clauses involves movement through spec-vP. We looked at the role of phases in relation to lexical selection, noting that only a subarray of the items in the lexical array can be accessed on any given phase. We raised a number of questions about phases. We began by exploring the relation between EPP-hood and phasehood; we presented evidence (from multiple wh-questions in Spanish) that intransitive light verbs may have a wh-attracting [EPP] feature, and yet not be phases. We went on to explore the possibility that DP and/or PP may also be phases, noting that any such claim requires us to make a number of ancillary assumptions (e.g. about feature percolation and [EPP] features). We took a closer look at what drives wh-movement, exploring a way of implementing Chomsky’s idea that an interrogative wh-word has an interpretable Q-feature and an uninterpretable wh-feature which makes it active, and conversely that an interrogative C has uninterpretable (and unvalued) Q- and P-features (with a non-interrogative C able to bear a P-feature but not a Q-feature). We noted that such an analysis would require us to suppose that yes–no questions contain an interrogative operator (e.g. a null counterpart of whether) in spec-CP. However, we also observed that the analysis proposed in the text left in its wake a number of unanswered questions for future research.