<![CDATA[Abstract The implementation of Clean and Healthy Living Behavior (CHLB), particularly the habit of washing hands with soap, plays a crucial role in maintaining students' health in the school environment. Along with the implementation of Indonesia's Free Nutritious Meals Program (Makan Bergizi Gratis/MBG), the need to promote and habituate proper handwashing before and after meals has become increasingly important. At the same time, the utilization of local natural resources, such as soapberry (Sapindus rarak), offers an environmentally friendly alternative to synthetic cleaning agents while serving as a contextual learning medium. This community service program aimed to enhance elementary school students' knowledge, practical skills, and environmental awareness through a STEM Project focused on producing natural hand soap from soapberry. The implementation consisted of the planning, preparation, socialization, hands-on soap-making practice, reflection, and evaluation stages. Program effectiveness was evaluated using pretest–posttest assessments, participant response questionnaires, reflection sheets, and product evaluation. The results indicated an improvement in students' knowledge after participating in the program. Participants' responses were categorized as Very Good, while reflection results demonstrated that students understood the benefits of soapberry as a natural cleansing agent and recognized the importance of maintaining personal hygiene and environmental cleanliness. The hand soap products produced by the participants were categorized as Good based on evaluations of color, aroma, clarity, packaging, and foam quality. These findings indicate that a STEM-based approach utilizing local resources can effectively support the implementation of Clean and Healthy Living Behavior while fostering environmental awareness through project-based learning experiences.]]>
