This paper is an extensive acoustic analysis of V-to-C and C-to-V coarticulatory effects in Catalan CV sequences for 18 consonants and 8 vowels. Data indicate that Catalan phonemes differ as to the degree of resistance to coarticulation and suggest strongly that differences in coarticulatory resistance follow from differences in degree of articulatory constraint. A theory of coarticulation is proposed that accounts for coarticulatory effects in terms of the articulatory constraints involved in the production of gestures for adjacent phonemes, indeperdently of considerations about the linguistic nature of the phonemic units under control. It is argued that such a theory is more likely to explain patterns of coarticulatory activity arising from compatible and conflicting gestures than previous coarticulation models.