Transforming growth factors (TGFs) are small polypeptides that were initially defined by their ability to induce transformation of non-neoplastic cells in culture. However, it has become increasingly clear that TGFs are not restricted in function to promoting cell growth. One type of transforming growth factor, TGF-beta, is a multifunctional molecule which has unique and potent effects on many target cells and tissues. In this article, Sharon Wahl, Nancy McCartney-Francis and Stephan Mergenhagen focus on the evolving role of TGF-beta in regulating inflammation, immune responses and tissue repair.