"Two and Two Make Zero" considers children's acquisition of numerical concepts from a wide range of perspectives including topics that are often overlooked, most notably: the principal properties of the counting numbers in and of themselves; the role that numerical symbols play in number acquisition; the underlying conceptual structure of number symbolization; the import of notational representation of numbers and the advantage of the Hindu-numeral system over the systems it replaced; and, finally, the role social/ parental inputs play in number development. "Two and Two Make Zero" also examines more widely discussed subjects such as the mental processes involved in number cognition and perception, number application in the physical world, the history of notational symbols, number origin, and the leading theories and studies concerning children's conception of number. By including these topics as well, "Two and Two Make Zero" offers a comprehensive review and analysis of children's number acquisition. (Contains 14 figures and 335 footnotes.)