Abstract. Berame JS, Lumaban NW, Delima SB, Mercado RL, Bulay ML, Morano AB, Parohinog CDMG. 2022. The attitude and behavior of senior high school students toward environmental conservation. Biodiversitas 23: 5267-5277. The worsening environmental problems have become a serious concern prompting humanity to search for solutions aiming for environmental management through understanding the relationship between human-environmental attitude and behavior with the belief that humans are the prime contributor to both - problem and the solution. By acknowledging this existing situation, this study was designed to assess the senior high school student’s level of understanding of and attitude toward the environment and the effects of both variables on their ecological behavior. A sequential strategy under mixed-method research was used in the study. A survey questionnaire containing both qualitative and quantitative questions was distributed to and answered by the respondents, followed by a focus group discussion that solidified and substantiated the quantitative result. Analysis of the responses demonstrated that students’ environmental attitudes were uncertain and connoted that they have intermediate attitudes and were all observed to be connected to their intermediate ecological behavior. Further, it revealed anthropocentric attitudes were dominant among students. This environmental attitude, together with human dominance over nature, denoted correlation along ecological behavior toward conservation policies, environmental threats and support for population growth policies, while eco-centric attitudes do not correlate to ecological behavior. In conclusion, the limited and ambiguous knowledge of senior high school students on the rule of human and nature need reinforcement for them to develop a good quality viewpoint about nature and willingly advocate environmental protection through their actions.