This document summarizes a workshop on data integration using ontologies. It discusses how data integration is challenging due to differences in schemas, semantics, measurements, units and labels across data sources. It proposes that ontologies can help with data integration by providing definitions for schemas and entities referred to in the data. Core challenges discussed include dealing with multiple synonyms for entities and relationships between biological entities that depend on context. The document advocates for shared community ontologies that can be extended and integrated to facilitate flexible and responsive data integration across multiple sources.