In this issue of Cancer Cell, Yaeger et al. report mutations, copy number variations, and selected rearrangements from a large series of metastatic colorectal carcinomas and primaries that produced metastases. The results provide important insights into differences in anatomical site of origin, age at onset, etiologic factors, and therapeutic responses. In this issue of Cancer Cell, Yaeger et al. report mutations, copy number variations, and selected rearrangements from a large series of metastatic colorectal carcinomas and primaries that produced metastases. The results provide important insights into differences in anatomical site of origin, age at onset, etiologic factors, and therapeutic responses.