Abstract: The community forest conservation is a means for decreasing deforestation and doing conservation correctly. The project for training of the community hardcores for the community forest conservation is very essential for the forest conservation, which will help them know how to do correctly and result in having people know how to do it in the same manner. This research aimed to study knowledge, opinions and behaviors of the community hardcores in conservation of the community forests and to compare knowledge, opinions and behaviors in conservation of the community forests of the community hardcores with different genders and years of study. The sample consisted of 35 students in the 1st and 2nd years of study, obtained by the use of the quota and the purposive sampling techniques in the Project of the University for Life at Chaiyaphum Rajabhat University. The instruments used for collecting the data included the training package for hardcores on community forest conservation, the test on knowledge, the questionnaire on opinions and behaviors in conservation of the community forests in 5 aspects: forest usage, forest maintenance, forest improvement and forestation, forest maintaining participation and related law and regulation. The statistics used for analyzing the data were percentage, mean, standard deviation and for testing hypotheses the paired t-test and f-test (1-way MANCOVA) were employed. The research findings revealed as follows: the hardcores as a whole and as classified according to genders and years of study showed gains in their knowledge about community forest conservation in general and in 3 aspects: forest usage, forest maintaining participation and related law and regulation, before the training at the 0.05 level of significance. Whereas, they did not indicate gains in the aspects of the forest maintenance and forest improvement and forestation before training and maintaining participation before the training (p<0.05). In addition, the 1st-year hardcores indicated gains in opinions about the maintenance aspect and the 2nd-year hardcores showed gains in the forest usage aspect before training (p<0.05). According to behaviors in conservation of the community forests, the hardcores as a whole and as classified according to genders and years of study showed gains in conservation in general and in each aspect at the 0.05 level of significance. Hardcores with different genders and the hardcores with different years of study did not indicate knowledge, opinions and behaviors in conservation of the community forests as a whole and in each aspect differently (p>0.05). The developed training program on the community forest conversation for community hardcores was appropriately efficient in developing knowledge, opinions and behaviors in conservation of community forest of those involved. This program should be supported to be implemented in training other hardcores in different communities in the future.