ABSTRACT (no. 2017-095) In 2012, the International Association of Oil and Gas Producers initiated “The Arctic Oil Spill Response Technology Joint Industry Program (JIP)” with nine companies funding projects in a wide range of technical areas. This paper summarizes results from the project “Dispersant Testing under Realistic Conditions”, a collaboration between SINTEF (Norway) and SL Ross (Canada). The objective of the research was to build on current knowledge to increase understanding of the effect of oil type, degree of weathering, and environmental conditions on dispersant effectiveness in ice-covered waters. SINTEF and SL Ross performed approximately 70 tests using two identical recirculating flumes with variable parameters such as oil types, dispersant type, mixing energy, ice coverage, and water salinity. The oils were weathered in the flumes for 6 or 18 hours under simulated winds, waves, and cold temperatures to represent weathering that might occur at sea prior to dispersant application. The dispersed oil was exposed to various mixing energies, starting with low energy waves, followed by somewhat higher energy waves, and finally by applying propeller wash. Four crude oils were studied and the dispersant efficiency of three commercial oil spill dispersants were evaluated for the tested oils. Other test parameters were ice coverage (50% and 80%) and water salinity (35, 15, and 5 ppt). Dispersant effectiveness as a function of the different test variables were estimated using results from the flume-based experiments. As expected, shorter weathering times resulted in an increase in dispersant efficiency. The dispersant effectiveness varied with both oil type and dispersant type applied, and the effectiveness increased when higher mixing energy conditions were used. Varying the ice cover did not influence the results significantly, but water salinity did, with the lowest dispersant efficiencies found at 5 ppt salinity. The conclusions are based on the findings from testing performed under the controlled conditions and may not be directly transferable to all conditions that could be encountered in the Arctic. However, this study shows that dispersants can be considered as a response option for spills in ice, but effectiveness needs to be validated in the field during an actual event.