áPreface. B. VanPatten; J. Williams; Introduction: The Nature of Theories. B. Van Patten; J. Williams; Early Theories in SLA. L. White; Linguistic Theory; Universal Grammar; and Second Language Acquisition. K. Bardovi-Harlig; One Function Approach to SLA: The Concept-Oriented Approach. N.C. Ellis; The Associative-Cognitive Creed. R. DeKeyser; Skill Acquisition Theory. B. VanPatten; Input Processing in Adult SLA. M. Pienemann; Processability Theory. S.E. Carroll; Autonomous Induction Theory. S.M. Gass; A. Mackey; Input; Interaction; and Output in Second Language Acquisition. J.P. Lantolf; S.L. Thorne; Sociocultural Theory and Second Language Learning. L. Ortega; Second Language Learning Explained? SLA Across Nine Contemporary Theories.