Transforming Growth Factor β (TGFβ) signaling influences most aspects of cellular function in addition to playing a major role in organ development, remodeling, and repair. Given the wide range of effects induced by TGFβ, it is not surprising that alterations in TGFβ signaling have been implicated in development and progression of many different cancer types. Within the context of breast cancer itself, TGFβ is known to have a dual nature, being both tumorsuppressive during early breast cancer development and tumor-promoting during breast cancer metastasis. Targets for breast cancer therapeutics are greatly needed to decrease morbidity and mortality from this devastating disease. Here, we summarize what is known about TGFβ in breast cancer progression and discuss potential TGFβ targets for breast cancer therapeutics. © 2010 Bentham Science Publishers Ltd.