From initially defining marriage as "between a man and a woman" to citing Stonewall as a civil rights milestone in his second inaugural address on Monday, here are the defining moments in how Obama's public pronouncements on gay rights have evolved.

October 26, 2004: "What I believe is that marriage is between a man and a woman" 

Running for the Senate in 2004, Illinois State Senator Barack Obama makes his stance on gay marriage pretty clear: he isn't for it. He supports gay people's rights to obtain civil unions and have the same hospital visitation rights as straight couples—but he claims his faith prevents him from fully supporting gay marriage.

August 16, 2008: Stands by religious definition of marriage

In an interview with Saddleback Church Reverend Rick Warren (the pastor who compared gay marriage to legalizing incest and presided over Obama's first inauguration), Sen. Obama reiterates his stance that marriage exists only between a man and a woman. In the heart of his first presidential campaign, Obama reiterates, "I believe that marriage is the union between a man and a woman." This time, though, he also says he won't support an amendment enshrining that definition in the Constitution.

October 27, 2010: Signals the beginning of his "evolution" on gay rights

He continues stonewalling on the specifics of how he'll address gay marriage, but President Obama tells a group of reporters that his views on the subject are "evolving." He says, "I have staff members who are in committed, monogamous relationships, who are raising children, who are wonderful parents. And I care about them deeply. And so while I’m not prepared to reverse myself here, sitting in the Roosevelt Room at 3:30 in the afternoon, I think it’s fair to say that it’s something that I think a lot about."

December 22, 2010: Signs the repeal of "Don't Ask, Don't Tell" 

Obama does away with the Clinton-era policies requiring members of the military to hide their sexuality. "We are a nation that welcomes the service of every patriot," he says on the occasion.  "We are a nation that believes all men and women are created equal.''

February 23, 2011: Says his administration won't defend the Defense of Marriage Act

Though he acknowledges that the federal law defining marriage as between a man and a woman, another Clinton-era measure, remains on the books, President Obama promises that the Justice Department will not stand by DOMA in court.  

June 29, 2011: Applauds New York for legalizing gay marriage

The President remains cagey, not committing to an effort to legalize gay marriage himself. But he congratulates the state of New York on legalizing gay marriage within its borders. 

May 9, 2012: Publicly supports gay marriage

Appearing on NBC's Meet the Press, Vice President Joe Biden says he's "absolutely comfortable" with full legal parity between same-sex and opposite-sex married couples. That sets the stage for President Obama to say a few days later in an interview with ABC News' Robin Roberts, "I think same sex couples should be able to get married." 

May 13, 2012: Featured on Newsweek's cover as the "The First Gay President" 

Shortly after Obama comes out in favor of gay marriage, Tina Brown puts him on the cover of her flailing magazine, photoshopping a multi-colored hula hoop—ahem—rainbow halo over his head and dubs him the country's "first gay President." Just to be clear, though, he is not the country's first gay President—just like he is not the United States' first Jewish, Asian, Muslim, Hispanic, or female President. 

December 2012: Pushes his home state of Illinois to legalize same sex marriage

The President doesn't like telling people how to do their jobs... but he will if he has to. "Were the President still in the Illinois State Legislature, he would support this measure that would treat all Illinois couples equally," Obama spokesman Shin Inouye tells the Chicago Sun-Times as the state legislature mulls over a law that would legalize same sex marriages in the state.

January 16, 2013: Replaces a pastor who backs gay conversion therapy with a gay-friendly priest for his second inauguration

The man who presided over today's ceremony, Rev. Luis León of St. John's Church in Washington, D.C., is a big improvement over Rick Warren and the first pastor tapped for the second inauguration. It comes to light that in previous sermons, Pastor Louie Giglio backed "pray-the-gay-away" therapies and even favorably cited Bible passages that could be read as dealing with the execution of homosexuals. León is brought in at the last minute, and he's a much more LGBT-friendly pastor. His Episcopalian parish welcomes gay members and performs same sex unions. 

Today, January 21, 2013: Becomes the first President to reference gay rights in an in inaugural address

In his second inaugural address, President Obama says: 

We, the people, declare today that the most evident of truths — that all of us are created equal — is the star that guides us still; just as it guided our forebears through Seneca Falls, and Selma, and Stonewall ... Our journey is not complete until our gay brothers and sisters are treated like anyone else under the law — for if we are truly created equal, then surely the love we commit to one another must be equal as well.