This thesis examines the efforts that the North Atlantic Treaty Organization (NATO) has taken regarding the standardization of rifles and small arms ammunition from the Cold War to the present day and the limitations of these standardization efforts. During the Cold War, NATO was unsuccessful at standardizing a common rifle and its member states only agreed to standardize ammunition calibers. This thesis will discuss the factors that prevented all of the alliance’s militaries from adopting the same rifle models and the problems associated with NATO’s ammunition standardization efforts. Many NATO members intend on procuring new small arms during the 2020s period but there are no plans for the adoption of a common NATO rifle. In the absence of a common rifle for the future, NATO needs to undertake efforts that would both modernize its small arms capabilities and improve the degree of standardization within the alliance.