: Project-Based Learning to Improve Learning Outcomes of Limnology in Biology Department. The purpose of Limnology course is to enable students to solve freshwater environmental problems through the application of environmental management concept. The purpose of research is to improve learning outcomes of students in limnology concepts understanding, ability to design projects, and ability to implement and communicate the result. This classroom action research is designed in two cycles. Research was conducted on Limnology course in the Biology Department, State University of Malang, in the second semester of the year 2009/2010. Project-based learning guided by cooperative group investigation can increase students' understanding of limnology concept, the students' ability to plan and implement limnology research projects, and their ability to communicate the result of the project