Dr. Wacholder leaves behind a legacy of research excellence in genetic epidemiology that is both diverse and remarkably deep. A statistician by training, he was sought out by colleagues across the Division to advise on critical methodological and analytic components of nearly all major undertakings of the Division over the past 30 years, exploring the causes of cancer from natural history studies through clinical trials. He had a keen sense of the underlying biological questions and succeeded in helping the rest of us to become smarter and better informed. His breadth ranged from studies of risk factors to the application of new technologies to investigate the heritable component of different cancers.