Law enforcement practitioners rely on a variety of behaviors to identify drug couriers in airports. Through consultation with subject matter experts, we cataloged 69 distinct behaviors. These behaviors relate to ticket characteristics, luggage characteristics, general behaviors, deceptive behaviors, verbal behaviors, nonverbal behaviors, and group behaviors. These 69 behaviors are used within specific environments to understand the importance of an individual s behavior. There are five pre-departure environments relevant to the use of these behaviors: pre-arrival, drop-off, ticket counter, security lane, and departure gate/terminal; and three post-arrival environments: arrival gate/terminal, baggage claim, and pickup. Further research is needed to identify the reliability and validity of the findings documented in this report.