Progesterone is indispensable for differentiation of human endometrial stromal cells (HESCs) into decidual cells, a process that critically controls embryo implantation. We now show an important role for androgen receptor (AR) signalling in this differentiation process. Decreased posttranslational modification of the AR by small ubiquitin-like modifier (SUMO)-1 in decidualizing cells accounted for increased responsiveness to androgen. By combining small interfering RNA technology with genome-wide expression profiling, we found that AR and progesterone receptor (PR) regulate the expression of distinct decidual gene networks. Ingenuity pathway analysis implicated a preponderance of AR-induced genes in cytoskeletal organization and cell motility whereas analysis of AR-repressed genes suggested involvement in cell cycle regulation. Functionally, AR depletion prevented differentiation-dependent stress fibre formation and promoted motility and proliferation of decidualizing cells. In comparison, PR depletion perturbed the expression of many more genes, underscoring the importance of this nuclear receptor in diverse cellular functions. However, several PR-dependent genes encode for signaling intermediates and knockdown of PR, but not AR, compromised activation of WNT/-catenin, TGF/SMAD and STAT pathways in decidualizing cells. Thus, the non-redundant function of the AR in decidualizing HESCs, centred on cytoskeletal organization and cell cycle regulation, implies an important role for androgens in modulating fetal-maternal interactions. Moreover, we show that PR regulates HESC differentiation, at least in part, by re-programming growth factor and cytokine signal transduction.