This research aims to improve junior high school student’s mathematical representation abilities with REACT strategy. This research used a quasiexperimental pattern with nonequivalent control group design. The subjects of this research were students of class VIII A and VIII B in SMP Labschool UPI, Bandung. The instrument used was test of mathematical representation abilities. The reliability coefficient of mathematical representation was 0.56. The conclusion was the improving mathematical representation abilities of students who received learning with REACT strategy higher than students who received the conventional learning. Keywords: improving, mathematical representation, REACT strategy