Jake Sheppard put the Royals ahead in the 58th minute when his cross from the right looped into the net.
Tyler Frost doubled the lead in the 77th minute with a fierce 20-yard shot. Sheppard was denied a late third when Alex Palmer tipped his effort on to the bar.
Teams finishing second to fifth will compete in the play-offs for the second promotion spot to Division 1.
Reading are five points clear of sixth-placed Fulham with three matches left.
Reading: 12 Mar v Aston Villa (A) PL2
West Brom: 12 Mar v Stoke (H) PL2