The term impulsivity is commonly used to describe a person who is prone to act on whim without considering the long-term consequences of his or her actions. Several different definitions and measures have been established to examine impulsive behaviour in a variety of populations such as substance abuse addicts, adolescents, brain-damaged patients and those who suffer from eating disorders. Impulsivity is a construct both complex and multi-dimensional. It has been characterised as an inability to inhibit appropriate behaviours or to delay gratification, acting without forethought or sufficient information and the failure to correct inappropriate responses. Its multiple descriptive features have led some to suggest that impulsivity is not a unitary construct, but rather comprises "several related phenomena which are classified together as impulsivity". It has been linked to various negative outcomes including criminality, delinquency, extramarital affairs and gambling. This book gathers the latest research from around the globe in this field.