Adam Le Fondre scored twice as Reading recovered from conceding a goal after just 14 seconds to end Crawley's hopes of another FA Cup adventure.
Crawley had reached the fifth round in each of the last two seasons and they made the perfect start at the Broadfield Stadium with Nicky Adams' 25-yard strike.
But Le Fondre and then Noel Hunt secured a half-time lead for Reading, with the lively right winger Garath McCready providing the assists on both occasions.
From looking vulnerable for much of the first half, Reading wrapped up the victory 10 minutes after the interval when Le Fondre rammed home his second goal from the penalty spot.
The Crawley players appealed that Hunt had been offside when he was fouled but to no avail and Reading had successfully negotiated one of the day's potential FA Cup upsets.
In doing so, Reading denied Crawley director of football Steve Coppell the cup shock he wanted against the team he first guided into the Barclays Premier League.
After a busy Christmas programme, the current Reading manager Brian McDermott made seven changes and for 44 minutes it looked like a gamble he might lose.
Crawley, buoyed by the early lead, looked more hungry, more organised and they exploited Reading's vulnerable defence without being able to add to Adams' stunning opener.
Supporters were still taking their seats when Ian Harte, captaining Reading for the first time, was robbed of possession by Adams, who cut in from the right and beat goalkeeper Adam Federici with a 25-yard strike into the top corner.
Crawley were not over-awed by facing Premier League opposition and it was they who made all the early running, with Reading fortunate not to fall further behind.
Billy Clarke saw his shot headed clear by defender Alex Pearce after working space in the Reading box and Adams tried another long-range effort, which this time flew wide.
Crawley were opening Reading's left flank with ease. Josh Simpson cut into the box and there were calls for handball when Sean Morrison dived in to block his cross.
Federici produced an acrobatic save from Joe Walsh's header before Reading, having weathered a storm for the opening 13 minutes, capitalised from their first real period of pressure.
After a succession of corners, McCleary stooped to meet Harte's cross with a cushioned header back to Le Fondre, who directed a first-time shot low past Crawleygoalkeeper Paul Jones.
Reading kept the pressure on but initially without reward. Jones blocked a fierce shot from Hunt, Walsh halted Le Fondre's break and the Crawley defence closed McCleary down quickly after the midfielder had tricked his way into the box.
Crawley continued to ask questions of the flimsy Reading defence, with Federici pressed into action to deny Simpson after another Harte mistake and then Clarke from close range.
But Reading snatched the half-time lead. McCleary's pace and trickery as he ran into the box left Crawley full-back David Hunt on his backside and Hunt turned the cross past Jones.
Reading looked far more composed when they emerged for the second half, with Jem Karacan glancing a header wide before Hunt went down under a challenge from Walsh.
Referee Anthony Taylor awarded the penalty, despite the Crawley protestations, and Le Fondre drilled his shot into the roof of the net.
The match was effectively over as a contest at that point as Reading's superior quality began to tell and they bossed the second half, although Le Fondre could not fashion a hat-trick.
The Reading striker was closed down quickly after being picked out by a delightful ball from Hal Robson-Kanu and then wasted a good opportunity with a poor first touch.
In between times, Crawley continued to work chances and Federici was called into action to stop another Adams shot from distance before blocking Mat Sadler's drive with his chest.
Hunt almost made it four for Reading in the closing stages but Crawley keeper Jones was equal to his fierce strike.
Full coverage of all today's FA Cup fixtures at ITV's Sports website here