A general introduction to the basics of O.'s 'Abstract Performance Grammar', a hypothesis about the human natural language processing faculties. In addition to some introductory chapters on the defining characteristics of language, the history of behaviorism and its evolution toward O.'s grammar, and the paradigm clash in psycholinguistics, the main body of the book is concerned with detailed investigations into this grammar: structure and meaning in cognizing; naturalness in cognizing and sentencing; on the primitive affective dynamics of 'and' and 'but'; salience dynamics and unnaturalness in sentence production; processing of unnaturally ordered sentences in comprehending.