The purpose of this research is to define the effect of project- based learning on students' attitude towards English classes. The study group of the research consisted of 51 students attending grade 10 at an Anatolian high school in the Western Black Sea region of Turkey. In the quantitatively designed research, the "control group pre-test--post-test design", one of the experimental designs, was applied. The "Scale of Attitude towards English Classes" was used as the data collection tool. The scale consists of 20 items and three sub-dimensions. The research data were compared by applying the Mann Whitney U test and the Wilcoxon Signed-Rank Test, calculating the standard deviation value and arithmetic average on the SPSS22 program. Results of the research indicate that there was a significant difference between the experimental group's pre-test and post-test scores in favour of the post-test. There was a significant difference between the experimental and control groups' post-test results in favour of the experimental group.