The purpose of this study was to determine how the adoption of metacognitive strategy in jigsaw cooperative learning method and inquiry method influences students’ achievement in Biology. The study was carried out by following pre-test post-test experimental design with one control group and two experimental groups. To guide this study, four hypotheses were stated and tested at 0.05 level of significance. A total of 105 students from Municipal Higher Secondary School, Tamilnadu, India were used as sample for the study. The tool Biology Achievement Test (BAT) was developed, validated and used. The results suggested that instruction in the metacognitive strategy improve the students’ biology achievement.