<b>Contents: Part I: </b><i>Background.</i> <b>M.D. Zeiler,</b> Behavioral Units: A Historical Introduction. <b>T. Thompson,</b> The Problem of Behavioral Units. <b>P. Meazzini, C. Ricci,</b> Molar vs. Molecular Units of Behavior. <b>P. Harzem,</b> The Language Trap and the Study of Pattern in Human Action. <b>Part II: </b><i>Basic Units of Analysis.</i> <b>P.N. Hineline,</b> Returning the Operant-Respondent Distinction. <b>M.D. Zeiler,</b> Behavior Units and Optimality. <b>D.M. Baer,</b> In Application, Frequency is Not the Only Estimate of the Probability of Behavior Units. <b>P.B. Dews,</b> Pharmacological Contributions to Experimental Analysis of Behavior. <b>Part III: </b>Language and Mathematics. <b>M.J. Marr,</b> Mathematics and Verbal Behavior. <b>A.C. Catania, D.T. Cerutti,</b> Some Nonverbal Properties of Verbal Behavior. <b>M. Sidman,</b> Functional Analysis of Emergent Verbal Classes. <b>R. Schnaitter,</b> Behavior as a Function of Inner States and Outer Circumstances. <b>Part IV: </b><i>Integration of Larger Units of Analysis.</i> <b>D. Lubinski, T. Thompson,</b> Functional Units of Human Behavior and Their Integration: A Dispositional Analysis. <b>P.E. Meehl,</b> Trait Language and Behaviorese. <b>J.L. Falk,</b> The Formation of Ritual Behavior.