Achieving malaria elimination requires considering bothPlasmodiumfalciparumand non–P. falciparuminfections. We determined prevalence and geographic distribution of 4Plasmodiumspp. by performing PCR on dried blood spots collected within 8 regions of Tanzania during 2017. Among 3,456 schoolchildren, 22% hadP. falciparum,24% hadP. ovalespp., 4% hadP. malariae, and 0.3% hadP. vivaxinfections.Most (91%) schoolchildren withP. ovaleinfections had low parasite densities; 64% ofP. ovaleinfections were single-species infections, and 35% of those were detected in low malaria endemic regions.P. malariaeinfections were predominantly (73%) co-infections withP. falciparum.P. vivaxwas detected mostly in northern and eastern regions. Co-infections with>1 non–P. falciparumspecies occurred in 43% ofP. falciparuminfections. A high prevalence ofP. ovaleinfections exists among schoolchildren in Tanzania, underscoring the need for detection and treatment strategies that target non–P. falciparumspecies.