© 2017 American Psychological Association. Commercial motor vehicle (CMV) drivers often multitask when driving to increase travel efficiency and to increase alertness. Secondary tasks have been shown to impact CMV driving differentially, and attentional resources have been posited as a key factor. However, underlying mechanisms of secondary task engagement on attention and task performance have not been fully examined. Additionally, it is unknown if attentional control moderates these differential effects of secondary tasks and task performance. The current study aimed to examine decrements in driving performance from a resource-control theory by determining the specific relation between attentional resources and attentional control. To achieve this goal, 2 objectives were determined. Objective 1 considered the differential impact of secondary tasks on attentional resources in CMV driving performance. Objective 2 investigated individual differences in attentional control in the sample of CMV drivers. Fifty CMV drivers (Mage = 39.8 years, SD = 8.36) completed the 10-min psychomotor vigilance task providing measures of attentional control and also drove in a CMV driving simulator 4 times while presented with 1 of 4 secondary tasks. Findings linked secondary tasks to attentional resources, which, consequently affected CMV driving performance. The mediating effect of attentional resources significantly differed among varying levels of attentional control.