Despite the ongoing use of rewards in education, there is still an open debate about the circumstances when extrinsically-valued rewards are considered to be effective. The current experiment attempted to address this question by investigating the effects of both extrinsic value (high vs. low value) and text difficulty (easy vs. difficult texts) on engagement and learning during an instructional learning task. Students' engagement was measured during learning by assessing two types of engagement: (1) affective (i.e., valence and arousal), (2) cognitive (i.e., mind wandering). Results indicated that extrinsic value and text difficulty impacted the two types of engagement differently. Specifically, extrinsic value had a negative impact on valence, but a positive impact on arousal and learning. This suggests extrinsic value can in fact be an effective motivator for learning, given the right context. Conversely, text difficulty had a negative influence on mind wandering. Theoretical implications and potential future directions are discussed.