Anemia of pregnancy remains highly prevalent in Senegal despite the national iron/folic acid (IFA) supplementation program, which consists of providing prescriptions to purchase IFA to women during prenatal visits. The purpose of this study was to provide a framework for recommendations to improve the effectiveness of the program. We determined the prevalence and risk factors of anemia in a cohort of 480 pregnant women at 6 prenatal health centers in Dakar; we compared compliance after 20 weeks of supplementation between women who received prescriptions at 3 control centers and those who received free IFA at 3 intervention centers; and we assessed the factors that influenced high and low compliance in both groups. Overall, 39% of women were anemic and 71% were iron deficient (ID). Twelve percent were infected with P. falciparum; 21% had intestinal helminthes, and 6.5% had Hb AS. Women consumed foods containing iron absorption inhibitors at high frequency. ID > quadrupled the risk of anemia; malaria and Hb AS also significantly increased the risk for anemia. Compliance was 48% and 86% in the control and intervention groups, respectively (P<.001). Anemia prevalence was 62% among controls versus 31% among interventions (P<.01); ID prevalence was 84% and 57% in the control and intervention groups, respectively (P<.01). Women with high compliance were motivated by 1) the perception of improved health upon taking the tablets, 2) the insistence by midwives that they take them, and 3) the mention that the tablets would improve health. Women with low compliance indicated 1) experiencing side effects that they associated with the tablets, 2) misunderstanding that they needed to continue taking the tablets throughout pregnancy, and 3) forgetfulness. Our findings indicate that for effective control of anemia in Senegal, iron supplementation is needed in addition to educating women about better food choices. Antimalarial chemoprophylaxis and helminthes screening should be made available to all women. In addition, increasing access to IFA and educating women about the health benefits of the tablets can dramatically increase compliance and therefore improve iron status and decrease the incidence of anemia.