Smiling during speech requires concurrent and often conflicting demands on the articulators. Thus, speaking while smiling may be modeled as a type of coarticulation. This study explores whether a context-invariant or a context-sensitive model of coarticulation better accounts for the variation seen in smiled versus neutral speech. While context-sensitive models assume some mechanism for planning of coarticulatory interactions [see Munhall et al., 2000, Lab Phon. V, 9–28], the simplest context-invariant models treat coarticulation as superposition [e.g., Joos, 1948, Language 24, 5–136]. In such a model, the intrinsic biomechanics of the body have been argued to account for many of the complex kinematic interactions associated with coarticulation [Gick et al., 2013, POMA 19, 060207]. Largely following the methods described in Fagel [2010, Dev. Multimod. Interf. 5967, 294–303], we examine articulatory variation in smiled versus neutral speech to test whether the local interactions of smiling and speech can be resolved in a context-invariant superposition model. Production results will be modeled using the ArtiSynth simulation platform ( Implications for theories of coarticulation will be discussed. [Research funded by NSERC.]