This chapter discusses the nature of the processes claimed to be involved in creole genesis – relexification, reanalysis and dialect levelling – and shows how they apply in that context. The mental process of relexification is argued to play a central role in creole genesis. As is advocated in Lefebvre and Lumsden (1994b), creole languages are formed when a group of people create new lexicons through relexification and use these relexified lexicons as the primary means of communication within the creole community. Section 2.1 discusses the formal representation of relexification. It is argued that this mental process is available to human cognition. Indeed, it has been shown to play a role in the formation of mixed languages (section 2.2) and pidgins (section 2.3) and in some cases of second language acquisition (section 2.4). The presence of substratal features in pidgins and creoles is generally attributed to calquing and transfer; however, the cases of calquing and transfer discussed in this chapter are argued to actually be the result of relexification. Section 2.5 presents the proposal that relexification plays a central role in creole genesis and shows how it applies in this context. But, although relexification is claimed to be the central process involved in creole genesis, it is not the only one. When speakers of a creole community start targeting the relexified lexicons rather than the superstratum language, two other processes are put to work in the development of the creole: reanalysis (section 2.6) and dialect levelling (section 2.7).