Stereoscopic 3D visualization expands flood risk assessment by adding depth and realism to the way hydrologic model results are displayed. This study explores the benefits of using stereoscopic 3D visualization in comparison to traditional 2D flood visualization methods to support flood risk assessment. A quasi-experimental approach was used to rate the helpfulness of using 2D and stereoscopic 3D visualizations to answer nine flood risk assessment questions. The results show that both 2D and stereoscopic 3D visualization are effective though sometimes complimentary with each approach having different strengths and weaknesses. Questions of assessing safety showed the greatest differences with 2D maps rated as unhelpful and stereoscopic 3D visualizations rated as helpful. Conclusions suggest that stereoscopic 3D flood visualizations are effective and will likely become more available as 3D modeling technology improves. They also suggest that more research is needed to explore the benefits of stereoscopic 3D flood visualizations for flood risk assessment and for expanding flood risk awareness to more stakeholders in the community.