This chapter examines the basic features of malaria the parasite and malaria the disease, the molecular aspects of the invasion of red blood cells, and the adhesion of infected red blood cells to host cells and receptors and their role in pathogenesis. It considers the pathology of anemia, which is a prominent feature of the disease, and outlines drug treatment and vaccine development for malaria, as well as genomic approaches to the study of the parasite, pathology, and prevention of the disease. The malarial parasite has a complex life cycle, alternating between humans and the female Anopheles mosquito, a liver and blood stage of growth, complex eukaryotic metabolic systems, and a panoply of mechanisms to evade protective host responses. The invasion of erythrocytes by malaria parasites is a complex process and requires many specific molecular interactions. The anemia of Plasmodium falciparum malaria is typically normocytic and normochromic, with a notable absence of reticulocytes.