Job-based psychological ownership arises when workers develop personal feelings of possession over various aspects of a job. Drawing on conservation of resources and regulatory focus theory, the current research adopts a resource-based perspective to suggest a double-edged effect on job performance, mediated by three forms of territoriality (marking, defending, expanding) and information exchange and moderated by individual regulatory focus. With a multistep process in Study 1, the authors develop and validate a territorial expanding scale. Among 358 employee-supervisor dyads, Study 2 tests the proposed model; job-based psychological ownership prompts employees to engage in territorial marking, defending, and expanding. Territorial defending correlates negatively with information exchange, territorial expanding is positively related to it, and territorial marking has no relationship with information exchange. Information exchange is positively related to job performance. Job-based psychological ownership impedes job performance through increased territorial defending and reduced information exchange, especially among employees with a prevention focus. It enhances job performance through increased territorial expanding and increased information exchange, particularly if employees have a high promotion focus. These findings have notable implications for research and practice. (PsycInfo Database Record (c) 2023 APA, all rights reserved).