The Immuno-Oncology Biomarkers Workshop will identify the next steps for action in immunotherapy biomarker development. It will provide a forum for energetic discussion about the collaborative efforts across several societies and consortia, make progress on identification and analysis of novel biomarkers, and tackle data analysis and specimen sharing. The final session will bring together representatives from the fields of immune-oncology research, infectious disease, autoimmune disease and cell biology to discuss opportunities for cross-disciplinary collaboration to advance biomarker development.