The Philippines is one of the world's top conservation priority areas, yet unique species in the country are threatened. However, Filipinos still have poor awareness of Philippine wildlife and the country's biodiversity situation. A resolution to this situation is pro-environmental behavior, which can be achieved as an indirect benefit of environmental awareness. A questionnaire was used to survey a group of Science, Technology, Engineering, and Mathematics (STEM) students in Grades 11 and 12 (n = 314) from the University of Santo Tomas Senior High School (UST-SHS) to gather data about their level of knowledge about biodiversity, international conventions and local initiatives for the environment, and level of awareness about the critically endangered endemic mammals (CEEMs) in the Philippines. Results showed that STEM students have a fair weighted mean value (3.51) about diversity and little knowledge (2.77) of the Philippines' critically endangered and endemic mammals. A weighted mean value of 2.54 results in a level of knowledge on the local and international initiatives about CEEM has been revealed in the study. Significant differences were also noted between the biodiversity knowledge and CEEM knowledge and the international and local initiatives and CEEM knowledge. The multiple regression analysis pointed out a significant 0.289 r value, which means that the likelihood is too weak or too small that it can be neglected or considered trivial. The researchers suggest that future studies increase the scope of respondents to help determine differences between STEM and non-STEM students and how environmental behavior, knowledge, and awareness correspond.