An impeachment investigation (also known as an “impeachment inquiry”) is an investigation or inquiry which takes place in relation to an impeachment or potential impeachment.
In some governments, such as Ireland, Singapore, and Turkey, impeachment investigations take place after an impeachment vote. In other governments, impeachment investigations precede a potential impeachment vote. In Hong Kong, a formal impeachment investigation is required before the Legislative Council can hold a vote on whether to impeach the chief executive of Hong Kong. In the United States, where impeachment-related investigations are commonly called "impeachment inquiries", they are not a required part of the impeachment process. However, when impeachment-related investigations are conducted in the United States, they usually precede a potential impeachment vote, with the investigations resulting in a recommendation as to whether an impeachment should take place.