Background: An interplay of emotional and cognitive aspects underlies academic performance. We focused on the contribution of such interplay to text comprehension. Aims: We investigated the effect of worry on comprehension and the role of two potential moderators of this effect: physiological self-regulation as resting heart rate variability (HRV) and working memory updating. Sample: Eighty-two seventh graders were involved in a quasi-experimental design. Methods: Students read an informational text in one of two reading conditions: to read for themselves to know more (n = 46; low-worry condition) or to gain the highest score in a ranking (n = 36; high-worry condition). Students' resting HRV was recorded while watching a video of a natural scenario. The executive function of working memory updating was also assessed. After reading, students completed a comprehension task. Results: Findings revealed the moderating role of HRV in the relationship between induced worry and text comprehension. In the high-worry condition, students with higher resting HRV performed better than students who read under the same instructions but had lower HRV. In contrast, in the low-worry condition, students with higher resting HRV showed a lower performance as compared to students with lower HRV. Finally, working memory updating was positively related to text comprehension. Conclusions: Our findings indicate that the cognitive component of anxiety, that is, worry, plays a role in performing a fundamental learning activity like text comprehension. The importance of physiological self-regulation emerges clearly. In a condition of high worry, higher ability to regulate emotions and thoughts acts as a protective factor.