Here, we demonstrate that SENP2, a desumoylating enzyme, plays a critical role in the control of adipogenesis. SENP2 expression was markedly increased upon the induction of adipocyte differentiation, and this increase was dependent on protein kinase A activation. Remarkably, knockdown of SENP2 led to a dramatic attenuation of adipogenesis with a marked decrease in PPARgamma and C/EBPalpha mRNA levels. Knockdown of SENP2 also caused a marked reduction in the level of C/EBPbeta protein but not in that of C/EBPbeta mRNA. Interestingly, sumoylation of C/EBPbeta dramatically increased its ubiquitination and destabilization, and this increase could be reversed by SENP2. In addition, overexpression of C/EBPbeta could overcome the inhibitory effect of SENP2 knockdown on adipogenesis. Furthermore, SENP2 was absolutely required for adipogenesis of preadipocytes implanted into mice. These results establish a critical role for SENP2 in the regulation of adipogenesis by desumoylation and stabilization of C/EBPbeta and in turn by promoting the expression of its downstream effectors, such as PPARgamma and C/EBPalpha.