This article explores the cerebral mechanism of reading aloud activities in L2 learners. These activities have been widely used in L2 learning and teaching, and its effect has been reported in various Asian L2 learning contexts. However, the reasons for its effectiveness have not been examined. In order to fill in this gap, two studies using a brain-imaging technique, near-infrared spectroscopy, were conducted in order to determine a cerebral basis for the effectiveness of reading aloud activities. Study 1 investigated learners with high L2 proficiency to show the difference in cerebral activation between L2 and L1 learners as they read a passage aloud. The effect of material difficulty was also examined in this study. Study 2 then examined learners with both high and low L2 proficiency to show the effect of material difficulty vis-a-vis the learners' L2 proficiency. The effect of repeated reading aloud activities was also investigated in this study. These studies show that: a) Reading aloud in L2 results in a higher degree of cerebral activation than reading aloud in L1. b) Reading material beyond learners' L2 ability aloud results in low brain activation. c) Repetition of the same normal reading aloud activity in L2 does not necessarily increase (or decrease) the level of cerebral activation. d) However, including a repetitive cognitively demanding reading aloud activity does cause high brain activation. On the basis of these findings, this article provides a cerebral basis for the effectiveness of reading aloud activities in L2 learning. (Contains 4 figures and 7 tables.)