Do collections have an expiration date? Shifting interests, evolving social contexts, and discursive developments influence when a collection or its presentation is said to be outdated and what that implies for the constraints on, or options for, the actions to be taken in response. The revision or reorientation of a collection presuppose a critical engagement with the criteria regarded as valid at the time, which concern the origins, composition, objectives, and significance of a collection, among other aspects. The contributions to this volume intertwine historical case studies with contemporary questions about the reasons and circumstances that give rise to the assessment that a collection has outlived its shelf life.