Immunology is one of the most rapidly evolving and interdisciplinary fields in the biological sciences. We keep learning about new immune cell types; their curious origins; and the seemingly fundamental roles they play in cancer, metabolism, the central nervous system, and beyond. It may seem surprising, but just a few decades ago, scientists knew little about what kinds of cells defined our immune defenses and their developmental origins. The 2019 Albert Lasker Basic Medical Research Award recognizes the contributions of Max D. Cooper and Jacques Miller for their discovery of B and T lymphocytes and for paving the path toward modern immunology. Cell's Sri Narasimhan had a conversation with Max Cooper about the early days in the field, his journey, and the road ahead. Excerpts from this conversation are presented below, and the full conversation is available with the article online.