It is suggested that molar streams of behavior are constructed of various arrangements of three elementary constituents (elicited, evoked, and emitted response classes). An eight-cell taxonomy is elaborated as a framework for analyzing and synthesizing complex behavioral repertoires based on these functional units. It is proposed that the local force binding functional units into a smoothly articulated kinetic sequence arises from temporally arranged relative response probability relationships. Behavioral integration is thought to reflect the joint influence of the organism's hierarchy of relative response probabilities, fluctuating biological states, and the arrangement of environmental and behavioral events in time.Key words: behavioral units, units of analysis, response class, organization of behavior, behavioral taxonomy, relative response probability PROTASIS An impala gamboling across an East African Serengeti plain or a 16-month-old child confronted with a novel toy presents seamless streams of kinetic motion, free of beginnings or endings. The scant frequency with which behavioral scientists have concerned themselves with identifying the fundamental units of behavioral phenomena is, in part, due to the conspicuous integrity of such naturally occurring episodes; indeed, at times they seem to defy scientific analysis. Of the unresolved issues facing behavior scientists, none is more central than the analysis and synthesis of the fundamental units of behavior. Analyzing continuously flowing behavior into basic components and then resynthesizing it is a major aim of behavioral science. This goal is predicated on an understanding of the fundamental units of which behavior is composed. KnowlAppreciation is expressed to Robert Hinde, whose helpful remarks improved the first draft of this paper, and to John Falk, M. Jackson Marr, Paul Meehl, Richard Meisch, J. Bruce Overmier, Roger Schnaitter, Murray Sidman, and Michael Zeiler, whose comments sizably improved the manuscript. We especially wish to express our appreciation to our friend and teacher, Kenneth MacCorquodale. We hope the ideas expressed in this paper are in keeping with the intellectual tradition he taught so effectively at the University of Minnesota for 37 years.Reprint requests may be sent to