The purposes of this research were to study and compare environmental knowledge, environmental ethics and environmental volunteers before and after integrated instructional activities of environmental education by using community-based learning and active learning, to compare environmental knowledge, environmental ethics and environmental volunteers of students with different gender and Grade Point Average (GPA). The sample used in the study were 89 the first year undergraduate students in Environmental Education program, Faculty of Environment and Resource Studies, Mahasarakham University, which was derived by purposive sampling in environmental studies course. The research tools were the integrated instructional activities of environmental education by using community-based learning and active learning, environmental knowledge test, environmental ethics test and environmental volunteers test. The statistics used for data analysis were frequency, percentage, mean, standard deviation and hypothesis testing using t-test, F-test (One-Way MANOVA, One-Way MANCOVA and Univariate Test). The results of the research showed that: (1) The students had average score of the environment knowledge, environmental ethics and environmental volunteers in the posttest higher than pretest statistical significance (p < 0.05); (2) There was no significant difference between average score of the environmental knowledge, environmental ethics and environmental volunteers of undergraduate students with different gender (p > 0.05); and (3) There was statistically significant difference between average score of the environmental knowledge, environmental ethics and environmental volunteers of undergraduate students with different Grade Point Average (GPA) (p < 0.05).