Bradford (30) 32
Tries: Deacon, Burgess, Solomona, Evans, Halley
Goals: Deacon 6
Harlequins (12) 24
Tries: Worrincy 2, Barker, Paul
Goals: Paul 4
Bradford restored some pride after Thursday's humbling defeat by Leeds to get the better of Harlequins.
The Bulls went 18-0 up inside the opening quarter as they took control of the game right from the kick-off.
Paul Deacon kicked six goals and scored one of his side's first-half tries, with Sam Burgess, Dave Halley, David Solomona and James Evans also crossing.
Quins scored tries through Michael Worrincy (2), Dwayne Barker and Henry Paul but were never in the hunt.
Bradford coach Steve McNamara
"We started well but our bodies took over after 25 minutes. I can't be too harsh but I'm certainly not happy with our overall 80 minutes.
"Quins were very good in the second half but we're just thankful we've got the two points. We've won three out of four without playing particularly well."
Harlequins coach Brian McDermott
"We certainly had more then enough chances to win that game.
"We attacked the second half and whenever you play like that you will drop some balls, but I will never discourage the players from playing like that.
"The first 10 minutes killed it. We didn't seem to have any resistance near our line and that hacked me off.
"We kept them tryless in the second half and if we'd have had that resistance from the off it would have been a different story."
Bradford: Halley, Evans, Sykes, Hape, Tadulala, Jeffries, Deacon, Lynch, Newton, Burgess, Solomona, Nero, Finnigan.
Replacements: Kopczak, Godwin, Cook, Harris.
Harlequins RL: Wells, Clubb, Gafa, Howell, Sheriffe, Hill, Paul, Temata, Randall, Ward, Worrincy, Purdham, Mbu.
Replacements: Haggerty, Melling, Barker, Grayshon.
Referee: A Klein (London)