ABSTRACT Dispersant use is most effective in the early stages of an oil spill, yet because there is thought to be so much case-by-case variation, decisions about whether and where to use dispersants have been made only after a spill occurs. These decisions require, at a minimum, hours, and may require days. Two major efforts to shorten this decisionmaking process have recently been completed. A multidisciplinary, multiagency task force under the auspices of the American Society for Testing and Materials developed ecologically based guidelines for dispersant use in marine environments. The guidelines for 13 different marine and coastal habitat types consider dispersant use both to protect and to clean the habitat. They also identify those habitats that should be most protected in the event of a spill. These guidelines should be useful references for regional response teams and other spill response planners as they develop site-specific dispersant use plans. The second project was developed by an American Petroleum Institute task force and contractor with input from federal and state government agencies. It is a site-specific method for planning whether to use dispersants in marine environments. It divides an offshore region into “dispersant use zones” based on ecological considerations. The method was applied to selected areas offshore southern California as a test.