Metastases, rather than the primary tumors from which these malignant growths are spawned, are culpable for greater than 90% of human cancer-associated mortality. Metastases arise through the completion of a series of cell-biological events – collectively termed “the invasion-metastasis cascade” – which involve the dissemination of tumor cells to distant organ sites and their subsequent adaptation to these foreign microenvironments. Importantly, a number of endogenous mechanisms exist that serve to prevent metastatic progression. These safeguards must be overcome by incipient metastatic tumor cells in order for them to generate detectable metastases. Here, I highlight four endogenous mechanisms that protect against the development of metastatic disease in breast carcinomas. I discuss how the expression of these genes are dampened during malignant progression, the downstream responses they orchestrate, and clinical opportunities to therapeutically target these mechanisms. Indeed, one potentially effective strategy for the remediation of metastatic disease involves the reactivation of endogenous anti-metastasis mechanisms. Therefore, knowledge regarding endogenous anti-metastasis mechanisms may both further our comprehension of the basic etiology of metastasis and also guide the treatment of human tumors.