Reds ground out a precious Sky Bet League One victory thanks to a goal from Mike Jones.
The midfielder scored his second goal of the season four minutes before the break with a composed finish after good work by man of the match Kyle McFadzean and Billy Clarke.
Colchester offered much more of a threat in the second half and twice hit the woodwork but Reds defended resolutely and have now conceded just once in their last four games at the Checkatrade.com Stadium.
John Gregory made two changes to the side that drew 1-1 at Shrewsbury with Matt Tubbs replacing Rory Fallon, who had a heel problem, and Andy Drury returning at the expense of Gary Dicker.
Reds were first to threaten on four minutes. Josh Simpson flicked on Drury’s pass to Tubbs who elected to shoot first time from the edge of the box but his effort was well wide.
The game took time to settle but Sam Walker in the Colchester goal was tested on the quarter-hour. Clarke tried to find the unmarked Drury in the box but when his cross was blocked he struck a volley which Walker grabbed at the second attempt. Clarke then found Jones in space and he cut inside from the left but shot straight at Walker.
Mark Connolly was booked for a foul on ex-Red Sanchez Watt and the defender was involved on 28 minutes when his pass to Simpson was flicked into the path of Jones, whose angled drive was deflected for a corner.
At the other end Freddie Sears tried his luck from 25 yards but his effort was never troubling Paul Jones.
Reds won a series of corners and their pressure was rewarded on 41 minutes. Clarke played a delightful ball over the defence into his path and JONES ran on to it, sidestepped Walker and slid it inside the far post for his second goal of the season.
Drury had the first effort of the second half when Clarke’s lay-off gave him space 20 yards out for a left-foot hit that went straight at Walker.
Colchester had threatened little at that stage but Watt went desperately close to equalising on 57 minutes when he met a cross from the left with a looping header which bounced off the top of the crossbar.
JG then made his first change with Jamie Proctor replacing Tubbs, who’d had a quiet afternoon, and when Proctor was pulled back by Tom Eastman on 65 minutes the ex-Reds loanee went into the referee’s book.
Reds had a great chance on 71 minutes when Proctor dispossessed Eastman to find Simpson eight yards out, but his shot was blocked by a defender.
Sergio Torres replaced Drury on 72 minutes then Colchester sub Clinton Morrison was booked for protesting at the award of a free kick.
Simpson had the ball in the net with ten minutes to go but was flagged offside and seconds later Colchester hit the woodwork again when substitute Dominic Vose rattled the left-hand post from 25 yards. As the game got stretched Proctor tested Walker from 12 yards after muscling past Eastman.
Colchester pushed men forward late on in search of an equaliser with Walker even coming up for a corner but Crawley defended solidly to protect a valuable three points.