The structural model of positive and negative cognition derives from principles of information processing, intrapersonal communication, and cybernetic self-regulation. The model proposes five distinct states of mind quantitatively defined by the proportion of positive to total cognition. A positive dialogue with a set point proportion of .618 plus or minus .06 is considered a functionally optimal balance because of information processing properties that render negative events maximally striking. States of mind that deviate from this optimal balance are associated with psychopathology. Specifically, mild dysfunction is characterized by an internal dialogue of conflict with a set point of .500 plus or minus .05 and moderate dysfunction by a negative dialogue with a set point of .382 plus or minus .06. Analyses of 27 studies of normal, anxious, and depressed subjects indicated that the model fit existing data. Insufficient data were available to evaluate the two extreme states of mind--positive monologue (greater than or equal to .69) and negative monologue (lesser than or equal to .31). The states of mind model provides a theoretical and empirical framework for the study of cognitive balance in development, psychopathology, and psychotherapy. (Data tables and graphs are included.) (Author)