Deficits in working memory (WM) have been reported repeatedly in children with primary language impairment (PLI) and may significantly contribute to the language difficulties that are experienced by these children. However, interventional studies within the field regarding the cross-domain effects between working memory and language are limited, and their results are contradictory. Therefore, the first aim of this study was to explore whether WM training can improve the WM skills of these children and whether the effects of training could be transferred to language, specifically to grammatical skills. The second aim of this study was to investigate the near and far transfer effects of direct language intervention on grammar and WM, respectively, as this is the most (and sometimes the only) considered treatment programme for children with PLI. Using a single-subject experimental design, ten 6-8-year-old children with PLI received WM training and language intervention, respectively, in two consecutive phases of study. The treatment gains on targeted areas and generalization to the other domain were tracked by