Drawing on a relational perspective to human resource development and management (HRD/M), a multilevel and multisource field study has been conducted examining how HRM practices of job interaction requirements/task interdependence and HRD practice of cross‐training interplay in order to enhance employees’ job/task citizenship performance (JCP). A two‐level research model from a sample of 43 organizations and 535 nested individuals demonstrates that socially enriched jobs (interactive and interdependent), when supplemented with organizational (system‐wide) cross‐training opportunities, increase extra efforts among employees to complete activities which are not part of their in‐role requirements. Thus, by applying a 1‐2‐1 moderation analysis, we offer new knowledge about social and cognitive aspects of human behavior above and beyond the traditional focus on narrowly defined job/task performance. In addition, we explicate how mutual understanding across job positions may practically contribute to achieving superior individual‐level JCP when relational architecture of the workplace is designed.