A fighting 96 at Headingley from Gloucestershire's Australian captain, Michael Klinger, condemned Yorkshire to yet another defeat in Group C of the Yorkshire Bank 40 and maintained his own side's place at the top.
Once again, Yorkshire's depleted one-day attack was unable to put their opponents under sufficient pressure as they chased a 241 target which they achieved with five wickets and 11 balls to spare.
Hamish Marshall and Klinger shared an opening stand of 74 in 12 overs, Marshall setting the tone by driving Moin Ashraf over long-off for six.
Teenage seamer Ben Coad gave away only one run in a tight first over and he went on to dismiss Marshall for 44, thanks to a great diving catch at deep leg slip by Iain Wardlaw.
But Klinger then found a more than capable partner in wicketkeeper Gareth Roderick, who came to the crease in place of Chris Dent who had left the field with a side injury during the Yorkshire innings.
The stand from the Gloucestershire pair had galloped on to 119 in 19 overs when Roderick tried to steer Wardlaw over the slip area and was caught behind for 63 from 66 balls with four fours and a six.
Alex Gidman had his middle stump knocked back by Richard Pyrah, who also had Benny Howell driving a high catch to Coad at mid-on, and Klinger robbed himself of a century by driving Ashraf to Ballance at mid-off, his 96 coming off 98 deliveries with six fours and three sixes.
That left Gloucestershire on 226-5 in the 37th over but they were still very much in charge and Ian Cockbain and James Fuller saw them safely home.
Yorkshire, who finished on 240-6, won the toss on a good batting pitch, however, the experiment of Pyrah opening the innings with skipper Andrew Gale failed once again, Pyrah tamely driving Graeme McCarter low to Howell at cover in the second over to leave the right-hander with only 29 runs from five knocks.
Gidman put down Phil Jaques as he dived to his right and there was another fortunate moment for the Australian left-hander when he top-edged Fuller just out of 17-year-old debutant Miles Hammonds' reach at mid-wicket.
Gale added 52 with Jaques but after striking 26 off 28 balls, he attempted an ungainly pull outside off-stump and presented Gidman with an easy catch at mid-wicket.
Ballance joined Jaques in a third-wicket partnership of 63, the highest of the innings, though Ballance survived a two-handed slip chance to Marshall and then a fierce on-drive to Gidman.
Off-spinner Hammond bowled much better than his final figures of one for 50 would suggest, his sole victim being Ballance when he holed out to Dent at deep backward square leg.
Jaques completed his half-century off 66 deliveries with five boundaries while Adam Lyth advanced to 30 with some stylish shots until he went back to cut at Gidman and was bowled.
Jaques was next to go. He moved well outside off-stump in a bid to paddle Gidman and was bowled. Andy Hodd drove at David Payne and was caught at slip by Klinger and it took an unbroken stand of 52 in seven overs between Rashid and Will Rhodes to give the score a reasonable look.