Ethical decision-making is key to the development of future engineers in our global and diverse society. The use of virtual worlds in Science, Technology, Engineering, and Math (STEM) education is an innovative use of technology in the classroom. This paper will describe how we developed, deployed, and assessed a novel approach to engineering ethics education that uses virtual worlds to teach ethics in STEM classes. Our project, SciEthics Interactive, is a 3-D virtual world where students take on various scientific roles and produce engineering reports in a hypothetical company producing genetically modified salmon. In this study, non-traditional students in both on-line and on-site classes participated in piloting this virtual world. Throughout their role-playing activities, different ethical dilemmas appeared. After the activity, student feedback was collected in the form of a survey, which will be used to further refine and improve the SciEthics virtual world and expand its use in teaching ethics as part of STEM curriculum.