Variation in the ability to maintain internal goals while resolving competition from multiple information streams has been related to individual differences in working memory capacity (WMC). In a multitask environment, task choice and task performance are influenced by internal goals, prior behavior within the environment, and the availability of relevant and irrelevant information in the environment. Using the voluntary task-switching procedure, task performance, as measured by switch costs, was related to WMC, but only at short preparation intervals. Task choice processes were only weakly related to WMC. These findings are consistent with models of cognitive control that separate task choice processes from the processes of activating and maintaining task readiness. WMC is related to regulation of specific task parameters but not to choice processes integral to the coordination of multiple sources of information.Keywords Working memory capacity . Task switching . Choice processing Mechanisms of cognitive control are central to optimal multitasking performance (Brown, Reynolds, & Braver 2007;Logan, 1985;Monsell, 2003). Cognitive control must be exerted in a multitask environment because the environment affords multiple behavioral paths and does not specify which task should be completed at any given moment. Guiding the completion of one task in the face of competition from other potential tasks requires the selection and activation of the task set, or group of component cognitive operations, necessary to carry out that task (Rogers & Monsell, 1995). The goal to perform a given task must be maintained and shielded from interference from other goals potentially applicable in the environment (De Jong, 2000). In addition, as the current task changes, no-longer-relevant task sets are deactivated (Mayr & Keele, 2000). This type of sequential control requires flexible updating and maintenance of the task rules. Different components of cognitive control are referred to as executive control, executive attention, or working memory.The demands of a multitasking environment-maintaining goals in the face of competition and distraction and updating goals as the environment changes-are functions that have been attributed to working memory. More specifically, measures of working memory capacity (WMC) are thought to tap the same set of functions. For example, WMC has been defined as "the attentional processes that allow for goaldirected behavior by maintaining relevant information in an active, easily accessible state outside of conscious focus, or to retrieve that information from inactive memory, under conditions of interference, distraction, or conflict" (p. 23; Kane, Conway, Hambrick, & Engle 2007). Individual differences in WMC are correlated with the abilities to resolve interference between memory representations (Rosen & Engle, 1998); to filter out distracting information (Conway, Cowan, & Bunting 2001); to act on the current task goal when habitual attentional orienting may lead to inaccurate responding, as in ...