Colic is a syndrome of persistent crying in infants, with multiple causes. In most cases, it is within the spectrum of normal variability in infant behavior and can be treated with reassurance, education, and counseling about appropriate parental responses. In a minority of cases, careful analysis of the crying pattern and other infant behaviors may suggest an underlying gastrointestinal problem that may be amenable to more specific treatment. This article explores the evidence supporting the use of crying and behavioral diaries to determine an appropriate response to each colicky infant.