This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by BioMed Central. ; Embryonic stem (ES) cells are intrinsically unstable and differentiate spontaneously if they are not shielded from external stimuli. Although the nature of such instability is still controversial, growing evidence suggests that protein translation control may play a crucial role. We performed an integrated analysis of RNA and proteins at the transition between na?ve ES cells and cells primed to differentiate. During this transition, mRNAs coding for chromatin regulators were specifically released from translational inhibition mediated by RNA-Induced Silencing Complex (RISC). This suggests that, prior to differentiation, the propensity of ES cells to change their epigenetic status is hampered by RNA interference. The expression of these chromatin regulators was reinstated following acute inactivation of RISC, and it correlated with loss of stemness markers and activation of early cell differentiation markers in treated ES cells. We propose that RISC-mediated inhibition of specific sets of chromatin regulators is a primary mechanism for preserving ES cell pluripotency while inhibiting the onset of embryonic developmental programs. ; We acknowledge the following grants: FIRB RBAP10L8TY (MIUR); Fondazione Roma and PAINCAGE FP7 Collaborative Project number 603191 (RB,MD); Flagship Project InterOmics PB.05 and MIUR-PRIN-2012 (FC); Wellcome Trust Core Grant reference 092096 and Cancer Research UK Grant Reference C6946/A14492 (LP).