As scientific and engineering efforts become increasingly global in nature, the need to understand differences in perceptions of research ethics issues across countries and cultures is imperative. However, investigations into the connection between nationality and ethical decision-making in the sciences have largely generated mixed results. In Study 1 of this paper, a measure of biases and compensatory strategies that could influence ethical decisions was administered. Results from this study indicated that graduate students from the United States and international graduate students studying in the US are prone to different biases. Based on these findings, recommendations are made for developing ethics education interventions to target these decision-making biases. In Study 2, we employed an ethics training intervention based on ethical sensemaking and used a well-established measure of ethical decision-making that more fully captures the content of ethical judgment. Similar to Study 1, the results obtained in this study suggest differences do exist between graduate students from the US and international graduate students in ethical decision-making prior to taking the research ethics training. However, similar effects were observed for both groups following the completion of the ethics training intervention.