The term compensatory lengthening (CL) refers to a set of phonological phenomena wherein the disappearance of one element of a representation is accompanied by a lengthening of another element. This study focuses on descriptive and formal similarities and divergences between CL of vowels triggered by consonant and by vowel loss.

To account for the full range of existing compensatory phenomena as well as for the absence of certain logically possible outcomes, it is necessary to distinguish synchronic and diachronic aspects of CL. It is shown that both CL through consonant and through vowel loss arise via phonologization of inherent duration of vowels and neither involves any transfer of length or weight. Rather, intrinsic phonetic vowel durations are reinterpreted as phonologically significant upon a change in the conditioning environment or syllable structure.

Though similar diachronically, CL through consonant and vowel loss function differently in synchronic grammars. Because of this split, purely phonological accounts are inadequate to predict the full typology of CL. It is proposed that the nature of the split is due to a difference in the relationship between trigger and target for the two types of CL.

The book is intended for phonologists, as well as for general linguists.