This study proposes a cross-situational specialization framework for what, at its introduction, was a newer generation personal computer (PC) device (a tablet computer). With use as the basis for continuance adoption as the theoretical lens, this study explores how the tablet co-exists as a substitute-and a complement-in-use with incumbent PC(s). To test a model consisting of cross-situational use patterns, determinants, and outcomes, this study develops and analyzes the results of a survey of tablet computer use in a learning and education context. The results show a stronger co-existence between the tablet and the incumbent devices when the devices perform the same tasks in different, compared to the same, situations. Additionally, use of the PC devices as distinct units depends more on the situational sophistication of their features for use than sophistication of the devices per se. Further, user perception of the tablet's in-use impact depends on its performance in situations where the incumbent devices have limited sophistication, while user perception of the tablet as an essential device depends on its extension of the uses of the incumbent devices to different situations. This study implies that when a newer generation personal mobile device is an imperfect substitute for incumbent PC devices, individual adoption of such a mobile device may facilitate a partial reversal of IT adoption in organizations.