This study investigated the effectiveness of explicit instruction in think aloud as a means to promote elementary students' comprehension monitoring abilities. Sixty-six fourth-grade students were randomly assigned to one of three experimental groups: (a) a Think-Aloud (TA) group, in which students were taught various comprehension monitoring strategies for reading stories (e.g., selfquestioning, prediction, retelling, rereading) through the medium of thinking aloud; (b) a Directed Reading-Thinking Activity (DRTA) group, in which students were taught a predict-verify strategy for reading and responding to stories; or (c) a Directed Reading Activity (DRA) group, an instructed control, in which students engaged in a noninteractive, guided reading of stories. The primary quantitative analyses involved two planned orthogonal contrasts-effect of instruction (TA + DRTA vs. 2 x DRA) and intensity of instruction (TA vs. DRTA)-for three whole-sample dependent measures: (a) an error detection test, (b) a comprehension monitoring questionnaire, and (c) a modified cloze test. Results of effect of instruction contrasts revealed that TA and DRTA students were more skillful at comprehension monitoring than DRA students (TA + DRTA>DRA for all three measures). Results of intensity of instruction contrasts indicated that although TA-trained students had greater awareness of comprehension monitoring abilities (TA>DRTA for the questionnaire), DRTA students' performance equaled (TA = DRTA for the cloze test) or exceeded (TA