How do allies successfully manage their alliance partnership in times of political crisis? We argue that the procedural norm of political contestation and the substantive norm of security consensus set the parameters for non-detrimental disagreement among democratic alliance partners. Rather than interpreting sharp disagreements with the US as signs of soft-balancing or alliance decline, we explain the seeming contradictions in alliance behavior — maintenance of the alliance versus sharp disagreements within the alliance — by drawing norms and institutions into the power equation. We use within- and cross-regional case comparisons of alliance disputes in East Asia and Europe to test our argument in both bilateral and multilateral contexts, respectively.