A vertical access device comprises a semiconductive base comprising a first source/drain region, a semiconductive pillar extending vertically from the semiconductive base, and a gate electrode adjacent a sidewall of the semiconductive pillar. The semiconductive pillar comprises a channel region overlying the first source/drain region, and a second source/drain region overlying the channel region. An opposing sidewall of the semiconductive pillar is not adjacent the gate electrode or another gate electrode. Semiconductive device structures, methods of forming a vertical access device, and methods of forming a semiconductive structure are also described.