Mind wandering, commonly defined as task-unrelated thought, is a shift of attention away from the external environment towards internally generated thoughts. Previous research has shown that mind wandering negatively affects inhibitory control, as measured by the Sustained Attention to Response Task (SART). However, these effects may also reflect differences in task difficulty rather than inhibitory control specifically. Therefore, a Random Dot Motion (RDM) task was included as a non-executive control task. The present study examined whether mind wandering related performance costs are specific to inhibitory control or reflect more general task difficulty effects. Participants (N=36) completed five laboratory sessions in which they performed both the SART and RDM task, while attentional state was assessed using intermittent thought probes. Accuracy was analysed using a generalized linear mixed effects model. Results showed significant main effects of difficulty and attentional state, indicating lower accuracy on hard than easy trials and during off-task states. A significant interaction between difficulty and attentional state revealed larger performance costs of mind wandering on more difficult trials. However, no significant three-way interaction between task, difficulty, and attentional state was found, suggesting that these effects did not differ between the SART and RDM. These findings indicate that mind wandering impairs performance, but is not specific to inhibitory control. Instead, mind wandering related performance costs appear to reflect more general task difficulty, particularly under higher task demands. Result are interpreted in light of the executive-resources framework. Limitations and directions for future research are discussed.