The study of Great Power behavior is a relevant and timeless pursuit, as the major powers can impact economies, societies, and lives around the world. Be it war, trade, or other assertions of interests abroad, such activities affect the global political landscape significantly. Important questions raised in the current literature revolve around issues such as: Why do Great Powers overexpand? And why do they expand at some points in time but not in others? This study asks, Why does a power expand differently in two similar situations at the same point in time? To probe such a question I explore McKinley's policy choices toward Cuba and the Philippines in 1898, the latter territory being annexed while the former not. Each case is presented against three competing explanations derived from recent expansionist literature. Propositions from each perspective--offensive realism, defensive realism and domestic coalition logrolling--are introduced in a structured, focused manner in each case. Despite the shortcomings of realism as a progressive paradigm for international relations inquiry, this study hints that a variant of realism-- offensive--could be a persuasive "first cut" theory at understanding foreign policy expansionism. At least, it is not apparent here that realism should be displaced by a domestic politics paradigm. Practically, what follows reveals the ability of Great Powers to expand 1s not necessarily thwarted due to internal characteristics (democratic, pluralist, "weak" state), whether they have popular support or not. The findings also suggest that it is out of confidence and opportunity that expansionism occurs in these cases, rather than out of insecurity. / Master of Arts