Grammont's Law of Three Consonants (LTC) states that French schwa is obligatorily pronounced in any CC_C sequence to avoid three-consonant clusters. Although schwa presence has been shown to be sensitive not only to cluster size but also to the nature of consonants in post-lexical phonology, the LTC is still considered as accurate to describe schwa-zero alternations in lexical phonology. The paper uses judgment data from French speakers in France and Switzerland to compare the behavior of schwa in derived words (lexical phonology) and inflected words (post-lexical phonology). The results show that schwa-zero alternations are conditioned not only by cluster size but also by cluster type in lexical phonology. Moreover, the same phonotactic asymmetries among consonant clusters are found in lexical and post-lexical phonologies. The data therefore support a weaker version of the lexical-phonology hypothesis than what is usually assumed for French. Lexical and post-lexical phonologies do not require different phonotactic constraints but only different weights for the same constraints
