Harlequins kept up their unbeaten start to the season with a 12th straight win to leave Gloucester scrapping for survival in the Heineken Cup.
First-half tries by full-back Mike Brown and centre Matt Hopper put Quins in charge and England number eight Nick Easter sealed the win late on.
Nick Evans kicked 13 points to leave Gloucester on the brink of elimination for a fifth time in six campaigns.
Gloucester could only manage three penalties through Freddie Burns.
In Pool Six, Harlequins share eight points with Toulouse, who trounced Connacht 36-10 but lead the table on points difference.
The Londoners play Toulouse in home and away fixtures in the next two rounds on 9 and 18 December.
At Kingsholm, Gloucester had their chances in attack, with Mike Tindall again impressive in the wake of his £25,000 fine and demotion from the England squad following the World Cup.
But it was Conor O'Shea's clinical Quins outfit that made their opportunities count.
The Premiership leaders took just six minutes to breach Gloucester's defence, when centre Jordan Turner-Hall fed Brown to slice through.
Evans converted, but Gloucester quickly went close through a trademark Lesley Vainikolo charge at the other end.
Burns and Evans exchanged penalties and another from the Gloucester man cut the deficit to four points, but Quins struck on the stroke of half-time.
Scrum-half Karl Dickson made the most of a decent build-up to put in Hopper for a try which was eventually awarded after consulting the television match official.
Evans' conversion attempt hit the left-hand post to leave Quins 15-6 at the interval, but another Evans penalty extended the lead straight after the restart.
Quins offered their opponents a lifeline by temporarily being reduced to 14 men when flanker Maurie Fa'asavalu was yellow-carded for a dangerous tackle on Akapusi Qera.
Burns kicked the resulting penalty to spark Gloucester's most threatening spell and it should have resulted in a try, but centre Henry Trinder spilled possession in contact diving over the line.
That was as close as Gloucester got and Quins sealed the victory when Easter raced clear in open play to touch down and round off another impressive afternoon.
Harlequins boss Conor O'Shea on the England manager's role: "My job is at Quins, full stop. No, I would not apply. No, the RFU have not been in touch.
"Players like Chris Robshaw and George Robson have committed to 2015, and I want to commit to them.
"We feel we are the start of a journey, not even midway through it. I will get a huge amount of pleasure if we are successful and we see a lot of guys go on to represent England.
"I want to be at Harlequins, and I am going to be at Harlequins."
O'Shea added: "This is one of the hardest places to come and get a result so I am delighted.
"We looked threatening when we had the ball, and we took our chances. We were clinical. Hats off to the boys.
"We were magnificent in defence. There is an energy among the players, and we have a hell of a lot of heart. Everyone gave everything out there."
Gloucester head coach Bryan Redpath told BBC Gloucestershire: "We were second best on many things, opportunities were created and not taken and some of our basic contact area and control of possession was poor for some reason.
"The nature of the game was big and we never underestimated Quins because we knew they were a dogged side and they've got some quality players around the team that can protect them.
"But when we create chances like we did and we don't take any then you're not going to win against a top side.
"There's no reason to blame any one individual but collectively we made too many mistakes. The disappointing part is that we lost a game at home when we've never really given ourselves a chance to win."
Gloucester: May, Sharples, Trinder, Tindall, Vainikolo, Burns, R Lawson, Wood, S Lawson, Harden, James, Hamilton, Buxton, Qera, Strokosch.
Replacements: Voyce for Vainikolo (41), Lewis for R Lawson (56), Murphy for Wood (71), Dawidiuk for S Lawson (60), Chistolini for Harden (71), Savage for James (59), Narraway for Buxton (71). Not Used: Taylor.
Harlequins: Brown, Stegman, Hooper, Turner-Hall, S Smith, Evans, Dickson, Marler, Gray, Johnston, Vallejos, Robson, Fa'asavalu, Robshaw, Easter.
Replacements: Casson for Hooper (73), Care for Dickson (46), Mayhew for Marler (72), Brooker for Gray (57), Fairbrother for Johnston (50), Matthews for Vallejos (73). Not Used: Wallace, Clegg.
Sin Bin: Fa'asavalu (47).
Ref: Christophe Berdos (France).