This book examines the burden sharing behavior of new NATO members. It makes the argument that new NATO members are burden sharing at a greater rate than older NATO members. It also suggests that NATO’s expansion did not lead to greater free-riding behavior in NATO, contrary to the predictions of the collective action literature. This analysis reveals that new NATO members have demonstrated the willingness to contribute to NATO missions, but are often constrained by their limited capabilities. This argument is supported using case studies, interviews with key NATO officials, and quantitative analysis of NATO defense expenditures and troop contributions.