Jones made up for a fielding gaffe with an RBI double in the sixth inning, leading Chicago to a 7-3 victory over the Philadelphia Phillies.
Chicago went 17-9 in July to close on the NL Central-leading Milwaukee Brewers.
Pat Burrell homered for the injury-depleted Phillies, who lost for just the second time in 11 games.
Leading 3-2 in the sixth inning, Phillies starter Adam Eaton (9-7) gave up back-to-back singles to Cliff Floyd and Mark DeRosa. Jones followed with a double down the line in left. Floyd easily scored from second, and DeRosa was held up at third but went home after Burrell bobbled the ball. DeRosa slid around catcher Chris Coste's tag to give the Cubs the lead.
"Guys are stepping up and picking other guys up. We're playing real good right now," said Jones. "When you're going for first place, you've got to do things like that."
Cubs starter Jason Marquis (8-6) pitched six innings, allowing three runs and eight hits. He struck out four and walked three.
Kendall gave the Cubs some insurance with a two-run single with the bases loaded off Phillies reliever Geoff Geary in the seventh inning, giving the Cubs a 7-3 lead.
During spring training, Cubs manager Lou Piniella said the Cubs needed "Cubby Swagger." Jones said the Cubs are playing with a sense of confidence.
"I don't know about a swagger, but there's a lot of excitement in here. There's a lot of guys who really don't think we're supposed lose," said Jones.
With the Phillies trailing 2-1 in the fifth and a runner on first, Jones didn't see the ball off Tadahito Iguchi's bat. The ball bounced a few feet behind Jones and into the stands for a ground-rule double. Jimmy Rollins followed with an RBI-groundout to tie the game.
"He didn't misjudge the ball, he just didn't see it. You don't see it, there is nothing you can do about it," Piniella said.
Alfonso Soriano led off the first inning with a grounder to shortstop. Rollins fielded it deep in the hole, but didn't have enough on the throw to get Soriano at first. Ryan Theriot followed with a bunt. Eaton slipped on the grass when fielding the ball, then threw off his back foot to first. The throw was off line and it went down the right-field line.
"We didn't play too good. We made three errors. Left 11 on base and couldn't get the big hit," said Phillies manager Charlie Manuel.
Soriano went into third and Theriot advanced to second on the error. Soriano scored on Derrek Lee's groundout, then Aramis Ramirez ripped Eaton's pitch off the wall in left for a double, scoring Theriot to give the Cubs a 2-0 lead.
Chris Roberson was 4-for-4, including an RBI single in the second inning.
Eaton pitched 5 1/3 innings and allowed five runs, four earned, and eight hits. He had two strikeouts and walked two.
"I just kind of got in my way a little bit in the first and sixth innings," said Eaton.
- OF Jayson Werth will be activated from the disabled list Wednesday to fill the vacant spot on the Philadelphia roster.
- The Phillies acquired reliever Julio Mateo from Seattle, adding bullpen depth shortly before Tuesday's deadline for making trades without waivers.
- Before the game, the Phillies acquired right-handed pitcher Gary Knotts from the Newark Bears.
- The last time the Cubs won 17 games in July was in 2000.
- Cubs reliever Kerry Wood pitched 1 2/3 scoreless innings for Double-A Tennessee in a rehab assignment. He struck out one and walked one.