We present the first study of nonnative English speech using real‐time MRI analysis. The purpose of this study is to investigate the articulatory nature of “phonological transfer”—a speaker’s systematic use of sounds from their native language (L1) when they are speaking a foreign language (L2). When a non‐native speaker is prompted to produce a phoneme that does not exist in their L1, we hypothesize that their articulation of that phoneme will be colored by that of the “closest” phoneme in their L1’s set, possibly to the point of substitution. With data from three native German speakers and three reference native English speakers, we compare articulation of read phoneme targets well documented as “difficult” for German speakers of English (/w/ and /dh/) with their most common substitutions (/v/ and /d/, respectively). Tracking of vocal tract organs in the MRI images reveals that the acoustic variability in a foreign accent can indeed be ascribed to the subtle articulatory influence of these close substitutions. This suggests that studies in automatic pronunciation evaluation can benefit from the use of articulatory rather than phoneme‐level acoustic models. [Work supported by NIH.]