In the present event-related functional magnetic resonance imaging study, the neural implementation of human working memory was reinvestigated using a factorial design with verbal and visuospatial item-recognition tasks each performed under single-task conditions, under articulatory suppression, and under visuospatial suppression. This approach allowed to differentiate between brain systems subserving domain-specific working memory processes and possible neural correlates of more "central" executive or storage functions. The results of this study indicate (1) a domain-specific functional-neuroanatomical organization of verbal and visuospatial working memory, (2) a dual architecture of verbal working memory in contrast to a unitary macroscopic architecture of visuospatial working memory, (3) possible neural correlates for a domain-unspecific "episodic buffer" in contrast to a failure to find brain areas attributable to a "central executive," and (4) competition for neuronal processing resources as the causal principle for the occurrence of domain-specific interference in working memory.