The first inauguration of Barack Obama as the 44th President of the United States took place on Tuesday, January 20, 2009.

The inauguration, which set a record attendance for any event held in Washington, D.C., marked the commencement of the first four-year term of Barack Obama as President and Joe Biden as Vice President. Based on the combined attendance numbers, television viewership, and Internet traffic, it was among the most-observed events ever by the global audience.