The Focus of Attention (FOA) is the latest incarnation of a limited capacity store in which a small number of items, in this case four, are deemed to be readily accessible and do not need to be retrieved. Thus a corollary of these ideas is that those items in the FOA are always immune to proactive interference. While there is empirical support for instances of immunity to PI in short-term retention tasks that involve memory for four-item lists, there are also many instances in which PI is observed with four-item lists as well as instances where PI and immunity to PI can be shown in the same experiment. In contrast to the FOA assumptions, an alternative cue-based account predicts both the presence of PI and immunity to PI as a function of the relation between the cues available and the particular test. Three experiments contrasted the FOA assumptions and the cue-based approach in a short-term cued recall task in which PI is manipulated by testing whether the presentation of previous, similar items would interfere with immediate recall of three list items. The results indicated that even with very short lists, both PI and immunity to PI could be observed. The PI effects observed in our experiment are at odds with the FOA approach and are more readily explained using the cueing account.