We used a corpus of radio and television speech to run a quantitative study of voicing assimilation in French. The results suggest that, although voicing may be gradient rather than all-or-none, voicing assimilation is essentially categorical. The amount of voicing assimilation little depends on underlying voicing but clearly varies with speech rate and also with consonant manner of articulation. The results also suggest that voicing assimilation, though largely regressive, is not purely unidirectional.