Abstract: The licensing of non-canonical argument constructions in modern Chinese has been a focus of debate among different theoretical frameworks. Generative approaches tend to divide the linguistic mechanisms involved into independently operating modules, while cognitive linguistic studies often focus on individual constructions in isolation. Both approaches fail to account for a crucial empirical fact: the acceptability of non-canonical argument constructions is subject to contextual regulation, e.g. through clausal juxtaposition. Drawing on the Cognitive Grammar view of argument realization and the Access-and-Activation model, this paper investigates the cognitive mechanism by which juxtaposition modulates the acceptability of non-canonical argument constructions. It is argued that juxtaposition enhances the focal prominence of non-core thematic roles through parallel processing, thereby enabling them to assume syntactic subject or object status. This analysis demonstrates the central role of focal prominence in Chinese argument realization, reveals the interaction among structure, discourse, and processing, and offers a unified cognitive account of non-canonical argument constructions in Chinese.