Expression of spatial motion shows wide variation as well as patterned regularities across the world's languages (Talmy, 2000), and events involving the traversal of a spatial boundary impose the tightest typological constraints in the lexicalization of motion, providing a true test of cross-linguistic differences. Speakers of verb-framed languages are required by their language not to use manner verbs in marking the change of location across boundaries (Aske, 1989). Here we test the strength of the boundary-crossing constraint and ask how speakers convey motion events when the constraints imposed by the experimental task are at odds with the constraints imposed by their native language. We address this question by comparing adult speakers’ description of motion scenes that involve the traversal of a spatial boundary in two typologically distinct languages: English and Turkish. Using an experimental paradigm that imposes competing demands with the semantic structure of Turkish, we compare Turkish speakers’ description of boundary-crossing scenes to that of English speakers. We find strong cross-linguistic differences in speakers’ verb choice (manner vs. path) and event segmentation (one vs. many), suggesting that boundary-crossing constraint can serve as a reliable test to detect the typological class of a language.