This study critiques traditional alliance theory because it fails to capture the nuanced alliance motivation and needs of small states. We argue that the concept of alliance “shelter” better explains small state alignment. The theory of alliance shelter has been developed to explain the alliance choices of Western small states, including Iceland, and serves as an important addition to alliance theory. Shelter is the diplomatic, economic, societal, and political alignment response of structurally weak states. Alliance shelter theory differs from traditional alliance theories for the following reasons. First, it regards small states as fundamentally different political, economic, and social units than large states. Second, their alliance shelter relationships are distinctly shaped by domestic as much as international factors. Third, small states benefit disproportionately from international cooperation, including institutional membership, compared with large states. Fourth, shelter theory claims that small states/entities need political, economic, and societal shelter (as well as strategic protection) in order to thrive. Fifth, the social and cultural relationships of the small states with the outside world are elements that have been neglected by alliance theory. Sixth, shelter may also come at a significant cost for the small state/entity. We conduct a plausibility probe of our argument against three contemporary non-Western cases: Armenia, Cuba, and Singapore. We find that the concept of alliance shelter explains their alliance behavior better than traditional alliance theory.