AbstractAsexual development (conidiation) in the filamentous fungusAspergillus nidulansis governed by orchestrated gene expression. The three key negative regulators of conidiation SfgA, VosA, and NsdD act at different control point in the developmental genetic cascade. Here, we have revealed that NsdD is a key repressor affecting the quantity of asexual spores inAspergillus. Moreover, nullifying bothnsdDandvosAresults in abundant formation of the development specific structure conidiophores even at 12 h of liquid culture, and near constitutive activation of conidiation, indicating that acquisition of developmental competence involves the removal of negative regulation exerted by both NsdD and VosA. NsdD’s role in repressing conidiation is conserved in other aspergilli, as deletingnsdDcauses enhanced and precocious activation of conidiation inAspergillus fumigatusorAspergillus flavus.In vivoNsdD-DNA interaction analyses identify three NsdD binding regions in the promoter of the essential activator of conidiationbrlA, indicating a direct repressive role of NsdD in conidiation. Importantly, loss offlbCorflbDencoding upstream activators ofbrlAin the absence ofnsdDresults in delayed activation ofbrlA, suggesting distinct positive roles of FlbC and FlbD in conidiation. A genetic model depicting regulation of conidiation inA. nidulansis presented.