Is psychology a science? Unlike Darwinian theory in biology or relativity and quantum theory in physics, psychology lacks the basic quantitative or conceptual foundation for a consensus view about how the mind works. Is psychology on the verge of developing such a foundation? 'Probably not', answers psychologist William R. Uttal in this iconoclastic and critical examination of psychology's underlying principles, assumptions, and concepts. In five in-depth chapters and one appendix, he explores the following key issues: what do we mean by 'science' and can psychology be legitimately described as a science; what are the general principles that should be applied to any science; what is the role of mathematics in psychology; given the current fragmented state of the discipline, is it possible to identify the general principles of a scientific psychology; and, is experimental psychology just applied epistemology and not really scientific. Uttal comes to the conclusion that psychology is a science only to the extent that it is behaviourist in orientation. By comparing his discipline to other sciences, he identifies its limits, establishes a set of principles that help to define psychology as a science, and suggests plausible future developments.