The status of these fields today is similar to that of medicine and surgery in the early 1700's, when practitioners acted more or less intuitively, received training mainly through apprenticeship, and relied on literature that consisted largely about aphorisms about appropriate actions. Similarly, negotiators use maxims on such topics as the need to enter a negotiation with a fallback position. These statements are important, but they should not be confused with theory. Theoretical statements are propositional in form, specifying relationships between variables. In addition, good theory also specifies moderator variables that influence the ways that other variables relate to one another. Finally, theory lends itself to empirical testing, whereas a maxim does not. Theory is also inherently flexible and can often be used to derive new knowledge. Field experiments are the ideal way to test theoretical notions about negotiation and mediation. Research findings have already produced many implications for the practice of mediation. A list of implications, descriptions of some research projects, and 15 references.