Pavel Pogrebnyak struck his third league goal for Reading to give Brian McDermott's side their second Barclays Premier League win of the season 1-0 at the expense of West Ham.
The Royals had halted a run of seven defeats with a draw at home to Swansea on Boxing Day and went one better against a poor Hammers side, moving three points clear of bottom club QPR in the process.
James Collins presented Pogrebnyak with a late Christmas gift. The Hammers defender looked to play a simple ball back to goalkeeper Jussi Jaaskelainen and Pogrebnyak stole in to slot past the Finn and put Reading ahead with just five minutes on the clock.
Royals' winger Jimmy Kebe was causing problems down the right flank early on and a 14th minute cut-back almost found Pogrebnyak but was well cleared. Two minutes later the same duo combined well on the edge of the area but Kebe's final ball drifted behind for a goal-kick.
West Ham struggled to make an impression in attack but skipper Kevin Nolan released Matt Taylor just before the half-hour mark, but his cross was collected by Reading goalkeeper Adam Federici.
The hosts gifted West Ham a half-chance in the final seconds of the first half as they dallied on the ball outside their own penalty area. Nolan pounced and found Gary O'Neil, but he appeared to be caught in two minds and his final ball was neither a shot or a cross.
Pogrebnyak had the ball in the back of the net again five minutes after the restart but was flagged offside after latching onto a through ball from Mikele Leigertwood.
Although the Hammers started to find their feet during the second half, they almost fell further behind when Jem Karacan's thunderous effort was tipped onto the bar by Jaaskelainen with Kebe firing the rebound into the crowd.
Reading managed to see out the closing stages to claim what could be a vital three points while West Ham's lack of away goals again proved their undoing.
The Hammers have only scored five goals on their travels in the league so far this season and the defeat leaves them only six points off the bottom three.