What factors influence the choice between alternative grammatical structures such as the following: a lit / a lighted cigarette, more full / fuller of convincing arguments, the main thesis of the book / the book's main thesis, take hostage a group of 15 holiday makers / take a group of 15 holidaymakers hostage, conceding that the argument is convincing / conceding the argument to be convincing? This is the central issue explored in this volume, which contains a unique selection of innovative in-depth empirical studies written in a broadly functional framework. The factors investigated include the following: phonological influences (such as the principle of rhythmic alternation and optimal syllable structure), frequency, pervasive semantic and pragmatic aspects (including iconicity, markedness, grammaticalization and typological tendencies), information structure, processing complexity and horror aequi (the avoidance of identity effects).