|Abstract:||In this paper, I examine systems of vowel reduction that employ two levels: moderate and extreme. Phonetically, the occurrence of extreme reduction seems to be linked to non-phonemic duration, and typically causes reduction in vowel sonority. Moderte reduction, on the other hand, can cause increases as well as decreases in vowel sonority. Based on this type of observation, I hypothesize that two-pattern vowel reduction systems utilize two distinct forms of reduction. That is, extreme reduction and moderate reduction are distinct phenomena, not 'stronger' and 'weaker' versions of a single process.