Methods to transiently and stably transfect blood stages of the human malaria parasite Plasmodium falciparum have been developed and adapted for gene-knockout, allelic replacement, and transgene expression in this organism. These methods are detailed in this chapter, as are approaches used to monitor transfectants during the selection process. The different plasmid vectors that are currently used for gene targeting and transgene expression (including green fluorescent protein expression) are also described.