The authors discuss the phenomenon of lying, a common psychic process that has received remarkably little scrutiny. The ubiquity of lying and others forms of deception suggests that they have "normal" aspects, but lying which is persistent or destructive to the quality of a person's life becomes pathological. Lying has many determinants, including developmental, biological, social, and psychodynamic. Antisocial, histrionic, narcissistic, borderline, and compulsive personalities have been associated with lying. The treatment of lying needs to be individualized according to the overall symptom complex in which it is embedded.