This paper provides an overview of phonetic research in our laboratory on phonological neutralization. Different kinds of neutralization are investigated, neutralization of manner of articulation and of voicing, as well as different languages, Korean and Dutch. In addition, data from both speech production and perception are presented. The Korean data suggest that neutralization of manner of articulation is phonetically complete and as such support the standard view in phonological theory. In contrast, the Dutch data indicate that neutralization of voicing is phonetically incomplete. Possible reasons for why some, but not other, phonological distinctions are completely neutralized are considered. A final experiment on the processing of Dutch cliticized forms rules out one of those reasons, the existence of multiple underlying forms. It is concluded that rather than calling the concept of linguistic contrast into question, incomplete neutralization in fact supports the standard phonological analysis of neutralization.