This discussion of the principal structures and factors that modify data in the decision making process considers individual-environmental structures in terms of their influences on data, as well as such factors as personality, cultural antecedents, data complexity, data load, task demand, and the individual's congruency with both the environment and the data as decision making variables. Interdisciplinary areas that can significantly contribute to an understanding of human information processing are identified, and consideration is given to the role libraries can and should play in the decision making process, with special attention to those libraries that serve administrators. (JEG)