We hypothesized that speakers adjust co-articulation in vowel–consonant (VC) sequences in order to provide listeners with enhanced perceptual cues to C, and that they do so specifically in those situations where primary cues to C place of articulation tend to be diminished. We tested this hypothesis in a speech production study of American English, measuring the duration and extent of VC formant transitions in five conditioning environments – consonant voicing, phrasal position, sentence accent, vowel quality, and consonant place – that modulate primary cues to C place in different ways. Results partially support our hypothesis. Although speakers did not exhibit greater temporal co-articulation in contexts that tend to diminish place cues, they did exhibit greater spatial co-articulation. This finding suggests that co-articulation serves specific communicative goals.