Although multiple perpetrator rape is a relatively under-researched area, a few authors have proposed theories to try to explain this complex phenomenon. The majority of these theories only examined some factors that are believed to play a part in multiple perpetrator rape (e.g., socio-cultural factors and group processes). The most recent and comprehensive model proposed is the Multi-Factorial Theory of Multiple Perpetrator Sexual Offending. This article critically examines this theory and the factors and processes that are suggested as contributing to multiple perpetrator rape (i.e., individual, socio-cultural and situational factors including the interactions between them). Some evidence is found to support this model although further research is needed to fully test it.