The bud emergence (BEM)46 proteins are evolutionarily conserved members of the α/β-hydrolase superfamily, which includes enzymes with diverse functions and a wide range of substrates. Here, we identified aPlasmodiumBEM46-like protein (PBLP) and characterized it throughout the life cycle of the rodent malaria parasitePlasmodium yoelii.ThePlasmodiumBEM46-like protein is shown to be closely associated with the parasite plasma membrane of asexual erythrocytic stage schizonts and exo-erythrocytic schizonts; however, PBLP localizes to unique intracellular structures in sporozoites. Generation and analysis ofP. yoeliiknockout (Δpblp) parasite lines showed that PBLP has an important role in erythrocytic stage merozoite development with Δpblpparasites forming fewer merozoites during schizogony, which results in decreased parasitemia when compared with wild-type (WT) parasites. Δpblpparasites showed no defects in gametogenesis or transmission to mosquitoes; however, because they formed fewer oocysts there was a reduction in the number of developed sporozoites in infected mosquitoes when compared with WT. Although Δpblpsporozoites showed no apparent defect in mosquito salivary gland infection, they showed decreased infectivity in hepatocytesin vitro. Similarly, mice infected with Δpblpsporozoites exhibited a delay in the onset of blood-stage patency, which is likely caused by reduced sporozoite infectivity and a discernible delay in exo-erythrocytic merozoite formation.These data are consistent with the model that PBLP has an important role in parasite invasive-stage morphogenesis throughout the parasite life cycle.