["Cognitive Science, Volume 50, Issue 5, May 2026. ", "\nAbstract\nAlthough psycho‐/neuro‐linguistics has assumed a distinction between morphological and syntactic structure building as in traditional theoretical linguistics, this distinction has been increasingly challenged by theoretical linguists in recent years. Opposing a sharp, lexicalist distinction between morphology and syntax, non‐lexicalist theories propose common morpho‐syntactic structure‐building operations that cut across the realms of “morphology” and “syntax,” which are considered distinct territories in lexicalist theories. Taking advantage of two pairs of contrasts in Mandarin Chinese with desirable linguistic properties, namely, compound versus simplex nouns (the “morphology” contrast, differing in morphological structure complexity per lexicalist theories) and separable versus inseparable verbs (the “syntax” contrast, differing in syntactic structure complexity per lexicalist theories), we report one of the first pieces of evidence for shared neural responses for morphological and syntactic structure complexity in language comprehension, supporting a non‐lexicalist view where shared neural computations are employed across morpho‐syntactic structure building. Specifically, we observed that the two contrasts both modulated neural responses in left anterior and centro‐parietal electrodes in an a priori 275:400 ms time window, corroborated by topographical similarity analyses. These results serve as preliminary yet prima facie evidence toward shared neural computations across morphological and syntactic structure building in language comprehension.\n"]