The role of domain-specific interference in the complex-span paradigm is still controversial. Here we distinguish two operations within the processing task of this paradigm-a cognitive operation to solve the task and a motor operation to give the answer. Their domain-specific interference with maintenance was investigated within the complex-span paradigm. Presentation of the memoranda-six words or four spatially distributed dots-was interleaved with the presentation of letter pairs to be processed. Cognitive operation domain was manipulated by asking participants to make either a rhyme judgment or a symmetry judgment for each letter pair. Motor operation domain was varied by requiring a response by either speaking or pointing. Cognitive load was held constant. Cognitive and motor operation showed separate domain-specific effects on memory: Visuospatial memory was impaired more by visuospatial than verbal cognitive operations and more by manual-spatial than oral motor operations. In contrast, verbal memory performance was worse when verbal cognitive operations and oral motor operations were executed. The results are discussed in relation to the multicomponent model, the time-based resource-sharing (TBRS) model, and the Serial Order in a Box-Complex-Span (SOB-CS) model. They imply that models of working memory must incorporate mechanisms that allow for domain-specific interference in the verbal and the visuospatial domain.