Headley, catcher Nick Hundley and shortstop Luis Rodriguez were named to the All-Star Game ballot Wednesday for the first time.
Adrian Gonzalez, a first-time All-Star in 2008, was another of the eight Padres named.
Gonzalez, the Padres' Gold Glove-winning first baseman, leads the team with five home runs and 11 RBIs, and is hitting .302. He again figures to be in consideration to make the National League All-Star team for the July 14 game at Busch Stadium in St. Louis.
The other Padres who are on the All-Star Game ballot are second baseman David Eckstein, third baseman Kevin Kouzmanoff, and outfielders Jody Gerut and Brian Giles.
"It was fun to vote because you knew you had a little impact on who would make the team," Headley said. "When I voted, we didn't have the Internet. When I went to games, I got excited about punching the ballot."
Fans can cast their votes for starters up to 25 times with the 2009 All-Star Game Sprint Online Ballot at MLB.com and all 30 club sites until July 2 at 8:59 p.m. PT.
"It's fun and a privilege to be a part of it," Headley said. "It's a privilege to be a Major Leaguer, period."
Starting rosters will be announced during the 2009 All-Star Game Selection Show presented by Chevrolet on TBS on July 5. Baseball fans around the world will then be able to select the final player on each team via the 2009 All-Star Game Sprint Final Vote at MLB.com.
And the voting doesn't end there. Fans will have the opportunity to participate in the official voting for the Ted Williams Most Valuable Player Award presented by Chevrolet at the Midsummer Classic via the 2009 All-Star Game Sprint MVP Vote at MLB.com.
The All-Star Game will be televised nationally by FOX and around the world by Major League Baseball International. ESPN Radio will provide exclusive national radio play-by-play, while MLB.com will offer extensive online coverage.
San Diego fans can make their All-Star selections at PETCO Park between May 4 and June 20.
"It's fun to be on the same ballot with some of the great players of the game," Headley said. "It's fun to have a chance. I was never one for card collecting or autograph collecting, but the All-Star Game is special."
A year ago, Gonzalez made his first All-Star Game appearance after being selected as a reserve for the team. He went 1-for-3 with a single and a sacrifice fly in a game eventually won by the American League, 4-3, in 15 innings.
Other than Gonzalez, only Eckstein (2005-06) and Giles (2000-01) have appeared in an All-Star Game, and that was when they were with other teams.