For self-regulated learning to be effective, students need to be able to accurately monitor their performance while they are working on a task, use this as input for self-assessment of that performance after the task, and select an appropriate new learning task in response to that assessment. From a cognitive load perspective, monitoring can be seen as a secondary task that may become hard to maintain and may hamper performance on the primary task (i.e., learning) under high load conditions. Therefore, this study investigated the effects of concurrent performance monitoring on cognitive load and performance as a function of task complexity. Task complexity was varied as between-subjects factor and monitoring as within-subjects factor. It was hypothesized that monitoring would significantly increase cognitive load and decrease performance on complex, but not on simple tasks. Results from a pilot study based on data from 31 participants seem to confirm this hypothesis.