Metacognitive enrichment has become an important component of modern mathematics instruction. This study investigates the effect of homework assignments enriched with metacognitive questions on students' mathematics achievement and homework behaviors. A quasi-experimental design with pre- and post-test measures and two groups (experimental and control) was employed to investigate the effect of the enriched homework. Forty-four students, 25 boys and 19 girls, participated in the study. The students in the experimental group responded to metacognitive questions as they worked on homework that otherwise was common to both groups. First semester mathematics scores taken from students' report cards were used as a pre-test of mathematics achievement; the mean of second and third examination scores were used as a post-test. The results revealed a significant difference between the mathematics scores of students who had been given homework assignments enriched with metacognitive questions and those who had not been given such homework.