Dr. King’s "I Have a Dream" speech was too carefully crafted to have been improvised entirely. The body of the text until roughly halfway through the speech was well-researched and written in advance of the March on Washington. However, the critical use of the words "I have a dream," which Dr. King repeats eight times during the speech, was somewhat improvised, according to the New York Times.

Dr. King had apparently already incorporated the phrase "I Have a Dream" and the ideas associated with it into earlier speeches before the March on Washington. The newspaper asserts that Dr. King was making the speech as written when, midway through, another participant at the march who had heard him use the dream theme before shouted from the speakers’ podium,

Tell 'em about the "Dream," Martin, tell 'em about the "Dream"!

The use of the phrase "I have a dream" is so powerful that the phrase has become what we know the speech as, and it certainly must have been extremely moving for all those who heard it delivered back during the civil rights movement.

Dr. King was a minister who was accustomed to delivering sermons from the pulpit. With the use of the words "I have a dream," his speech took on an almost liturgical proportion that transcended that one day and made it relevant for history. It became almost a gospel hymn. In fact, according to the newspaper, people in the crowd were swaying and clapping their hands, saying "amen" after each refrain of "I have a dream."