The inauguration of Donald Trump as the 45th president of the United States marked the commencement of Donald Trump's term as president and Mike Pence's term as vice president. An estimated 300,000 to 600,000 people attended the public ceremony held on Friday, January 20, 2017, at the West Front of the United States Capitol in Washington, D.C. The event was the 58th presidential inauguration. Held in Washington, D.C., from January 17 to 21, 2017, inaugural events included concerts, the swearing-in ceremony, a congressional luncheon, parade, inaugural balls, and the interfaith inaugural prayer service. The inauguration was protested worldwide.

Since 1937, the United States presidential inauguration has included one or more prayers given by members of the clergy. Since 1933 an associated prayer service either public or private attended by the president-elect has often taken place on the morning of the day. At times a major public or broadcast prayer service takes place after the main ceremony most recently on the next day.