How do interpreters manage to cope with the adverse effects of concurrent articulation while trying to comprehend the message in the source language? In Experiments 1-3, we explored three possible working memory (WM) functions that may underlie the ability to simultaneously comprehend and produce in the interpreters: WM storage capacity, coordination and word knowledge. In Experiments 1 and 2, interpreters, high span individuals and control participants performed free recall tasks under normal, articulatory suppression conditions (Experiment 1) or while performing a secondary task (Experiment 2). In Experiment 3, professional interpreters free recalled nonwords or words in their first (L1) and second language (L2). The results indicated that the ability of the interpreters to simultaneously comprehend and produce is related to word knowledge rather than to an increased WM storage capacity or to an enhanced ability to coordinate processes and tasks. [This research was supported by the Ministerio de Ciencia y Tecnologia.]