Investigation
Investigation or Investigations may refer to:

Law enforcement
 Investigation, the work of a detective
 Investigation, the work of a private investigator
 Criminal investigation, the study of facts, used to identify, locate and prove the guilt of an accused criminal
 Criminal investigation department, the branch of British Police force to which plainclothes detectives belong
 Federal Bureau of Investigation, the primary investigative arm of the US Department of Justice
 Griffin Investigations, the most prominent group of private investigators specializing in the gambling industry

Medicine
 Clinical trial, an investigation conducted to collect data for new drugs or devices
 Investigational New Drug, category in a USFDA program
 Investigations, tests and scans done to help with the diagnosis or management of a disease (see: medical test), although investigation may also refer to the general diagnostic process

Science and maths
 Forensic science investigation, in fields such as accounting, science, engineering and information technology
 Investigations in Numbers, Data, and Space, a K-5 mathematics curriculum

Arts, entertainment, and media

Literature
 The Investigation (play), 1965 play by Peter Weiss 
 The Investigation, 1959 book by Stanisław Lem

Television
 Investigation (TV channel), a Canadian French-language specialty channel
 Investigation Discovery, a digital cable channel
 "Investigations" (Star Trek: Voyager), the 36th episode of the television series Star Trek: Voyager

Other uses in arts, entertainment, and media
 Investigate (magazine), a magazine
 Investigation (film), a 2006 Bulgarian drama
 Investigative journalism, the practice of in-depth reporting or analysis
 Temporal Investigations, agency of the government of the United Federation of Planets in the fictional universe of Star Trek