The aim of this study is to determine the effect of computer-supported collaborative learning (CSCL) using GeoGebra software on 11th grade students' achievement in exponential and logarithmic functions. This study was carried out with quasi-experimental design consisting of a pre-test and a post-test with the experimental group and the control group. The study was conducted with 35 11th grade students (18 for the experimental group, 17 for the control group) in Istanbul, Turkey. The experimental group was taught through CSCL activities using GeoGebra software, while the control group was taught through textbook-based direct instruction. Data were collected via the mathematics achievement test (MAT) developed by researchers and consisted of 20 multiple-choice items. MAT was administered to both groups as a pre-test and a post-test. Data were analysed with SPSS-17.0 package program using t-test and ANCOVA. Results revealed that CSCL using GeoGebra software had significant effects on students' achievement in exponential and logarithmic functions.