Object-based attention accounts assume that visual attention selects one object at a time and more efficiently processes properties belonging to the attended object relative to properties belonging to different objects. Within-object superiority (faster RTs and fewer errors for targets on the same object than for targets on different objects) supports object-based attention accounts. However, a contrasting effect, between-object superiority, has also been found. The present nine experiments were designed to distinguish between within-object and between-object superiority effects in objects with occlusion. The present results showed that between-object superiority can be obtained for occluded objects and that this effect is influenced by the probability that the targets appear on the same object or different objects and is eliminated by object preview. A whole-object matching theory was discussed to explain between-object superiority and to extend our understanding of object-based attentional selection.