Nearly all types of cancer have the ability to metastasize, or spread from one organ or tissue in the body to another. Metastatic disease is responsible for the majority of cancer deaths and, therefore, is a critical area of research. Work to better understand the metastatic cascade-how cells detach from a primary tumor, migrate through the body, and seed secondary tumors at distant locations-will lead to improved treatment options for patients with cancer. Written and edited by experts in the field, this collection from covers the recent progress that has been made in understanding the molecular mechanisms underlying metastasis and how this knowledge is paving the way for new therapeutic targets. The contributors discuss progress in defining mutations that might be driving metastasis, the formation of a premetastatic niche and how it enhances the establishment of a secondary tumor, and how changes that occur during aging increase the metastatic capacity of tumor cells. They also consider the selection and colonization of common target organs (e.g., brain, liver, and bones) during metastasis and the roles of immune cells and extracellular vesicles at different steps of the metastatic cascade. Cellular plasticity-including evidence for metastatic stem cells and the role of tumor cell dormancy in recurrent metastasis-is also covered. In addition, the authors describe the development of in vivo models and techniques for studying metastasis, methods for monitoring tumor progression and metastatic spread (e.g., intravital microscopy and liquid biopsy), and immunotherapies that can potentially target cancer metastasis. This volume is therefore a vital reference for all cancer biologists and clinician-scientists concerned with defeating cancer.