The cries of infants and children are familiar to essentially all adults, and we all have our own common sense notions of the meanings of various cries at each age level. As is often the case, in the study of various aspects ofhuman behavior we often investigate what seems self­ evident to the general public. For example,if an infant cries, he or she needs atttention;if the cry is different than usual, he or she is sick; and when we areupsetby othermatters, children's crying can be very annoy­ ing. As a pediatric clinician often faced with discussing with parents their concerns or lack of them with respect to their children's crying, these usual commonsense interpretations were frequently inadequate. As this book illustrates, when we investigate such everyday behaviors as children's crying and adults' responses to crying, the