This paper adopts a cognitive linguistic framework to explore the influence of spatial and social factors on the use of Spanish demonstratives esta ‘this’ and esa ‘that’. Twenty adult Spanish speakers in Monterrey, Mexico, were asked questions prompting the selection of puzzle pieces for placement in a 25-piece puzzle located in the shared space between the participant and an addressee. Although participants were not explicitly instructed to produce demonstratives, the need to identify specific puzzle pieces naturally elicited a total of (...) 523 tokens of esta and esa. Analyses of the distribution of esta versus esa show that demonstratives are not used in a categorical manner to mark differences in physical space. Although participants tended to produce proximal esta for referents near the speaker, both esta and esa were used for referents further from the speaker and closer to the addressee. Participants’ demonstrative selection was also influenced by interaction type: intersubjective misalignment between speakers promoted the use of proximal esta, whereas intersubjective alignment promoted the use of distal esa. These results support the view that nominal grounding is an intersubjective activity. Physical and social factors jointly shape speakers’ construal of the developing co-constructed communicative event as a whole, leading to increasingly variable usage of demonstratives as the referent is more distant both spatially and intersubjectively from the speaker. (shrink)