Marcus Tudgay scored the only goal of the game as Nottingham Forest continued their resurgence under Steve Cotterill.
Tudgay's 75th-minute strike earned Forest their third win in four games since the former Portsmouth manager took over at the City Ground.
The home side could have found themselves ahead at the break, but Robbie Findley's first-half effort was ruled out for offside.
Goalscorer Tudgay also came close to giving Forest a first-half lead but his swiveled shot from Radaslow Majewski's cross flew over the bar.
The former Derby forward did score in the second period in a similar fashion, controlling substitute Andy Reid's ball before turning and firing past Adam Federici in the Royals net.
Reading boss Brian McDermott brought on Jimmy Kebe and Simon Church in an attempt to salvage a point but the Reds hung on to claim the victory.
