This document discusses identity management in the Open PHACTS project. It describes how the Open PHACTS Discovery Platform integrates data from multiple sources and resolves identity using an identity resolution service. This service uses mapping data and rules to infer connections between entities with different identifiers but representing the same real-world object. The document evaluates the performance of different approaches for including co-referent URIs in SPARQL queries using this identity resolution system. It finds that computing identity mappings improves coverage but query expansion via an external service introduces some overhead.