1. Tonight: Chris Hayes recaps a huge week in the push for same sex marriage. Camilla Taylor, the marriage project director in the Midwest regional office of Lambda Legal and Josh Barro, politics editor at Business Insider and MSNBC contributor, join us.
2. We're following up on Chris' take on the "1% pathology" with Josh Harkinson, a reporter with Mother Jones.
3. The union vote in Chattanooga, Tenn. comes to a close tonight. Will workers from the plant that makes Volkswagens decide to join the UAW?
4. Plus, a shocking look at how one school is preparing itself for an active shooter scenario. NBCNews.com's Nona Willis Aronowitz covered the story and joins All In tonight. Dahlia Lithwick, senior editor at Slate, and Shannon Watts, founder of Moms Demand Action for Gun Sense in America, discuss.