endosomal sorting complexes required for transport (ESCRT) drive membrane budding and scission reactions during multivesicular body (MVB) biogenesis, cytokinesis, HIV-1/Ebola release, plasma membrane repair and nuclear envelope reformation. On endosomes, five ESCRT complexes mediate the sorting and incorporation of ubiquitinated membrane proteins (cargo) into intralumenal MVB vesicles (ILVs) for lysosomal degradation. ESCRT-0, -I and II interact with cargo on the MVB surface. Previous studies have begun to shed light on the molecular mechanisms of ESCRT-mediated membrane remodeling, with special emphasis on the ESCRT-III complex. In particular, the ESCRT-II induced, ordered assembly of the four ESCRT-III subunits Vps20, Snf7, Vps24 and Vps2 into a ring-shaped complex has been shown to be required for membrane remodeling and scission during ILV formation. The AAA-ATPase Vps4 disassembles and recycles the ESCRT-III complex, thereby terminating the ESCRT pathway. A mechanistic role for Vps4 in ILV-formation has been unclear. By combining yeast genetics with biochemistry and electron tomography we find that ESCRT-II triggered ESCRT-III assembly on endosomes is required to induce or stabilize the necks of growing ILVs. Yet, ESCRT-III alone is not sufficient to complete ILV biogenesis. Rather, binding of Vps4 to ESCRT-III, coordinated by interactions with Vps2 and Snf7, couples ESCRT-III disassembly to membrane neck constriction during ILV formation. Thus, Vps4 not only recycles ESCRT-III subunits but also cooperates with ESCRT-III to drive distinct membrane remodeling steps that lead to efficient membrane scission at the end of ILV biogenesis in vivo. Based on these findings we propose that ESCRT-III and Vps4 function together as a membrane remodeling machinery.