The human ESCRT pathway comprises more than 30 different proteins, and this complexity is expanded further by associated regulatory and ubiquitylation machinery. Functional studies have identified a minimal core set of human ESCRT proteins, machinery that is essential for HIV-1 budding. ESCRT-1 recruitment follows an unusal path. The PTAP motif in p6 mimics the ESCRT-1 recruitment motif, bypassing the need for ESCRT-0. The TSG101/ ESCRT-I and ALIX both function by recruiting downstream ESCRT-III and VPS4 complexes, which in turn mediate membrane fission and ESCRT factor recycling.