The research program evaluates the cost effectiveness of the procedures for testing oil spill dispersants as specified in Annex X of the National Oil and Hazardous Substances Pollution Contingency Plan. The testing procedure is described in detail in the Standard Dispersant Effectiveness and Toxicity Tests (EPA Report EPA-R2-73-201) and in Annex X. These procedures were examined using No. 2 and No. 6 fuel oils and six commercial oil spill dispersants. The methods were evaluated in terms of reliability, precision, cost-effectiveness, and applicability. Seven laboratory methods for testing dispersant effectiveness using commercial oil spill products and No. 2 and No. 6 fuel oils were evaluated. The tests included the EPA, Mackay, Russian, French, Warren Spring, and two interfacial tension test methods (one based on the du Nouy ring principle and the other on drop weight). These tests were reviewed in terms of type, scale, method of applying mixing energy, and the time required to conduct a product evaluation. The experimental results, compared in terms of the precision of the test data and how effective the six nonionic dispersants were, demonstrate that the relative effectiveness found for the dispersants varies appreciably as a function of the testing method. Reasons for the variation are discussed, and recommendations are presented on how to achieve dispersant testing data that are more representative of open-sea conditions.