This monograph examines the syntax of bare infinitival and participial complements of perception verbs in English and other European languages, and investigates the general conditions under which verbal complement clauses are licensed. The introductory chapter is followed by an overview of the major syntactic and semantic characteristics of non-finite complements of perception verbs in English. The third chapter presents an analysis within the framework of Chomsky's (1995) Minimalist Program according to which event-denoting complements are minimally realised as projections of an aspectual head. In the next chapter, it is argued that verbs capable of licensing aspectual complement clauses must be able to function as a special type of control predicate, an assumption which is shown to account for a number of seemingly unrelated properties of the constructions under consideration. The final chapter examines syntactically reduced clausal complements from a cross-linguistic perspective, showing that Southern Romance languages differ from Germanic ones with respect to the availability of 'bare' aspectual complement clauses, a difference that is attributed to morphological properties of verbs in these languages.