: This study utilized a classroom action research which was conducted in two cycles, each cycle consists of planning, action, observation and interpretation, as well as analysis and reflection. Subjects were 42 year XI IPS 1 students at SMA Negeri 3 Sukoharjo. The data was validated using both techniques and methods triangulation. The researcher utilized descriptive quanlitative analysis. The results showed that the implementation of project-based learning model improve the quality of learning in accounting subejct among year XI IPS 1 students in SMA Negeri 3 Sukoharjo. The improvement was in the learning process and from the learning outcomes. The indicators of the learning process are: (1) increasing number of active students during apperception, (2) the involvement of students during the discussion increase, (3) the involvement of students during the discussion, ask questions and opinions increase. In terms of learning outcomes, the indicator is an increasing in student mastery.