A roller assembly for a sliding door that slides along a track includes an anti-jump member engageable with the track to prevent the roller assembly from derailing. The roller assembly comprises a bracket adapted for attachment to the door, a roller mounting member slidably seated in the bracket, and a roller rotatably mounted on the roller mounting member for travel along the track. The anti-jump member is pivotably supported in and displaceably carried by the roller mounting member for movement between an extended operative position wherein an engagement portion on the lower end thereof rides in the track, and a retracted inoperative position, wherein the engagement portion is spaced upwardly from the track. The roller assembly is operable to slide the door with the anti-jump member in either the operative position or the retracted position.