 This is a double-blinded, randomized controlled trial of 200 HIV-infected pregnant women living in Tororo, Uganda, an area of high malaria transmission. HIV-infected pregnant women between 12 and 28 weeks gestation will be randomized to receive enhanced malaria chemoprevention with monthly dihydroartemisinin-piperaquine DP versus monthly DP placebo. Their HIV-exposed children will receive the same prevention regimen from 2 to 24 months of age to which the mothers were randomized. All women will receive daily trimethoprim-sulfamethoxazole TS throughout the study per Uganda Ministry of Health guidelines. Children will also receive daily TS from 6 weeks to 24 months of age. TS will be considered a study drug only in infants and children beginning 6 weeks after cessation of breastfeeding and upon exclusion of HIV infection. Women and their children will be followed for 36 months after delivery. In a subset of the study population, the investigators will conduct an intensive pharmacokinetic study that will evaluate pharmacokinetic exposure of DP and EFV. The investigators will also measure HIV-related outcomes among the women enrolled in the study. The investigators will test the hypothesis that for HIV-infected mothers and HIV-exposed infants, that enhanced versus standard malaria chemoprevention in HIV-infected pregnant women and their children will reduce the incidence of malaria among children from 0 to 24 months of age and improve the development of naturally acquired antimalarial immunity. 