In General American English (GAE), tense/lax vowel contrasts occur before syllables ending in /l/ (e.g., peel, pill), but not those ending in /ɹ/ (e.g., peer; no [i]/[ɪ] contrast). No such restrictions occur after a syllable-initial liquid consonant (e.g., lip, leap, rip, reap). This study investigates the hypothesis that these phonotactic asymmetries arise from the interaction of differences in gestural coordination between nuclear vowels and liquid consonants in syllable onset versus coda position (Browman & Goldstein 1995) and differences in blending parameter strength for GAE laterals versus rhotics. A study of speech production by four GAE speakers was conducted using real-time Magnetic Resonance Imaging (Narayanan et al. 2004). Liquid consonants were produced in various vocalic environments and syllable positions (syllable-final, syllable-initial: word-initial and intervocalic). Analysis using a center of gravity metric defined by midsagittal lingual outlines points to greater articulatory stability in rhotics versus laterals across different vocalic contexts and less coarticulatory displacement of pre-lateral vowels than pre-rhotic vowels. Further analysis of spatial and temporal effects in the data will be used to test hypotheses about coordination of vowel and liquid consonant gestures in different syllable positions and their relation to phonotactic patterns. [Research supported by NIH and ARC.]