Here are all the candidates who qualified for the second debate:
Sen. Michael Bennet, D-Colorado
Former Vice President Joe Biden
Sen. Cory Booker, D-New Jersey
Montana Gov. Steve Bullock
South Bend, Indiana, Mayor Pete Buttigieg
Former HUD Secretary Julian Castro
New York City Mayor Bill de Blasio
Former Rep. John Delaney, D-Maryland
Rep. Tulsi Gabbard, D-Hawaii
Sen. Kirsten Gillibrand, D-New York
Sen. Kamala Harris, D-California
Former Colorado Gov. John Hickenlooper
Washington Gov. Jay Inslee
Sen. Amy Klobuchar, D-Minnesota
Former Rep. Beto O’Rourke, D-Texas
Rep. Tim Ryan, D-Ohio
Sen. Bernie Sanders, I-Vermont
Sen. Elizabeth Warren, D-Massachusetts
Author Marianne Williamson
Entrepreneur Andrew Yang
Who is out?
Five other candidates failed to make the cut for the July debates: former Sen. Mike Gravel, D-Alaska; Miramar, Florida, Mayor, Wayne Messam; U.S. Rep. Seth Moulton, D-Massachusetts; former U.S. Rep. Joe Sestak, D-Pennsylvania, and billionaire activist Tom Steyer. Only Gravel met the fundraising criteria. None of the five met the polling criteria.
Who is debating on which night?
Here is the lineup for each night's debate:
On the stage for the first night of the debate will be in order from left to right, Marianne Williamson, Tim Ryan, Amy Klobuchar, Pete Buttigieg, Bernie Sanders, Elizabeth Warren, Beto O'Rourke, John Hickenlooper, John Delaney and Steve Bullock.
On stage on the second night of the debate will be, from left to right, Michael Bennet, Kirsten Gillibrand, Julián Castro, Cory Booker, Joe Biden, Kamala Harris, Andrew Yang, Tulsi Gabbard, Jay Inslee and Bill de Blasio.
What about the next one?
According to the DNC, to qualify for the debates in September and October, candidates must have 2% in four qualifying polls and at least 130,000 individual donors. The first two debates allowed candidates to qualify by having either the showing in the polls or enough unique donors.
WATCH: Highlights from Second Night of First Democratic Presidential Debate