Recent evidence suggests that, during the production of CV syllables, (1) movement endpoints are coordinated in time and (2) the speed of the vowel movement covaries with the magnitude of CV overlap. This challenges existing theories in which (1) coordination is based on movement onsets and (2) movement parameters are invariant with respect to time-varying kinematics. We hypothesize that endpoints are coordinated via online variation in stiffness, an abstract parameter controlling movement speed. My dissertation project will pursue this hypothesis through both modeling and empirical work. On the modeling side, we will bidirectionally couple the neural dynamics governing movement parameter generation with the articulatory dynamics governing vocal tract movement. On the empirical side, we will analyze existing electromagnetic articulography (EMA) data in order to address methodological questions regarding movement landmark measurement, as well as theoretical questions regarding temporal variation in stiffness and cross-linguistic variation in CV coordination.