Collective collections are multiple local collections described and/or managed as a single collection. Constructing, understanding, and operationalizing collective collections is an increasingly important aspect of collection management for many libraries. This article presents some general insights about collective collections, drawn from a series of studies conducted by OCLC. These insights identify salient characteristics of many collective collections and serve as a starting point for developing collective collection-based strategies for such library priorities as shared print, digitization, and group-scale discovery and fulfillment.