Linguistics 49–5 (2011), 1137–1162 0024–3949/11/0049–1137 DOI 10.1515/LING.2011.031 © Walter de Gruyter Articulatory constraints on stop insertion in consonant clusters* DANIEL RECASENS Abstract This study claims that, in contrast with previous proposals in the literature, essentially all instances of stop epenthesis in two consonant clusters (e.g., [ml] > [mbl], [ls] > [lts], [wl] > [wgl]) may be attributed to the articulatory requirements and aerodynamic constraints involved in the production of the original cluster. The inserted stop results from the perceptual categorization of a transitional closure event. Several mechanisms may give rise to this momen- tary stoppage of air, and to an intraoral pressure rise which causes the stop burst to become prominent enough so that the emergent stop can be success- fully perceived. Apparently exceptional cases such as [nl] > [ngl] and [sl] > [skl] are accounted for through direct epenthesis assuming that [l] is strongly dark and thus, produced with a back postdorsal constriction. Data on stop deletion in consonant clusters appear to be in support of this production-based explanation of stop insertion. 1. Introduction Phonologists have formulated several explanatory hypotheses in order to ac- count for stop epenthesis in two consonant clusters. The present investigation will show that, while making relevant predictions on several regularities about underlying stop insertion, these proposals fail to explain a good number of facts. Based on available experimental evidence and on descriptive data from different languages, the major claim of this paper is that stop epenthesis is trig- gered by the formation of an oral closure at the boundary between the two consonants in the cluster which results from the ways in which the articulatory gestures for the two consonants overlap in time. Consequently, an adequate understanding of the stop insertion processes occurring in consonant clusters can only be achieved through an analysis of the articulatory and aerodynamic mechanisms involved in their production. A central argument of this approach