This study focuses on assistant principals, the ''forgotten future workforce'' of educational leadership. We explored the current landscape of assistant principalship within the context of work performance, including both task and discretionary performance, and the future career aspirations of assistant principals from a cross-national perspective. Specifically, the study aimed to fulfill the following objectives: (a) to identify the factors affecting the task and discretionary performance of assistant principals, (b) to identify the factors affecting three future career aspirations of assistant principals, and (c) to determine whether the influences of these factors differ by national origin. Personal initiative and perceived organizational support (POS) were the independent variables. This study also examined the demographic attributes of the participants and their schools. Two randomly selected samples, which composed of 227 Turkish and 144 American assistant principals were the participants. The data-gathering instrument incorporated the revised versions of the Personal Initiative Scale (Fay & Frese, 2001), the Perceived Organizational Support Scale (Eisenberger, Huntington, Hutchison, & Sowa, 1986), and the School Organizational Citizenship Behavior Scale (DiPaola & Tschannen-Moran, 2001). The findings of the study showed that personal initiative and POS significantly predicted the task performance, discretionary performance, and certain future career aspirations of assistant principals. National origin appeared to be a significantly differentiating factor of the assistant principals' task performances, discretionary performances, and future career aspirations. We drew conclusions and provided suggestions for future research.