Older adults commonly experience declines in cognitive control, which significantly impacts their well-being. Although intensive language training, particularly interpreting, holds potential for mitigating these declines, its efficacy remains largely unexplored. Based on previous findings in the literature (especially our theoretical framework on interpreting), we designed a 24-hour programme of Between-Dialect Interpreting Training (BIT). Using a pretest-intervention-posttest design, we evaluated the efficacy of the BIT (over 8 weeks) against a control group on general cognitive ability (MoCA) and core cognitive control functions – working memory (via listening span and digit backward tasks), interference control (via Stroop and Flanker tasks) and cognitive flexibility (via colour-shape task and WCST). Results demonstrated notable between-group differences favouring the BIT, with significant improvements in listening span, Stroop effect and Stroop global RT, colour-shape switch cost and marginal improvements in digit backward score and MoCA. The implications of how language training promotes cognitive health during ageing are discussed.