Skinner distinguished between two complementary aspects of science – experimental analysis and interpretation (Skinner, 1957, 1974; see also Donahoe, 1993; Donahoe & Palmer, 1989, pp. 25-129, Donahoe & Palmer, 1994; Palmer & Donahoe, 1992). Some phenomena occur under circumstances that permit essentially all of their determining antecedents to be manipulated and all of their relevant consequences to be measured. Research seeking to uncover the necessary and sufficient conditions for reinforcement using model laboratory preparations is directed at phenomena of this sort. However, many phenomena – and almost all complex phenomena – occur under circumstances that cannot meet these requirements. Phenomena of this latter sort are typically products of complex contingencies involving many biobehavioral processes acting concurrently over prolonged periods of time. Even if experimental analysis had successfully characterized all of the constituent processes, uncertainty would continue to enshroud the origins of these phenomena: The initial conditions and the sequence in which the selecting contingencies acted would remain at least partially unknown. To maintain that complex phenomena cannot be subjected to experimental analysis does not preclude them from being incorporated within science. However, for interpretation to be compelling, other methods must supplement experimental analysis.