Inducible gene expression underlies the epigenetically inherited differentiation program of most immune cells. We report that the promoter of the FOXP3 gene possesses two distinct functional states: an “off state” mediated by the polycomb histone methyltransferase complex and a histone acetyltransferase-dependent “on state.” Regulating these states is the presence of a Kruppel-like factor (KLF)-containing Polycomb response element. In the KLF10−/− mouse, the FOXP3 promoter is epigenetically silenced by EZH2 (Enhancer of Zeste 2)-mediated trimethylation of Histone 3 K27; thus, impaired FOXP3 induction and inappropriate adaptive T regulatory cell differentiation results in vitro and in vivo. The epigenetic transmittance of adaptive T regulatory cell deficiency is demonstrated throughout more than 40 generations of mice. These results provide insight into chromatin remodeling events key to phenotypic features of distinct T cell populations. Background: Epigenetic regulation of the T regulatory cell transcriptional program remains unclear. Results: Without KLF10, Polycomb permanently silences FOXP3, the master transcription factor of T regulatory cells. Conclusion: Chromatin remodeling events mediated by KLF10 and Polycomb regulate FOXP3 through a Polycomb response element. Significance: Polycomb and KLFs may direct a heritable, broadly applicable regulatory circuit within T cell development.