The WHO issued a strong recommendation that pregnant women be provided calcium supplements to prevent preeclampsia. This is the first recommended nutritional intervention to prevent this condition, a leading cause of maternal mortality globally. As health systems seek to implement this new intervention, a number of issues require further clarification and guidance, including dosage regimen, supplement formulation, and alignment with other antenatal nutritional interventions. We summarize key evidence on the above points and offer our views on good practices. Most developing countries have low calcium intake, so where habitual calcium intake is unknown, calcium supplements are likely beneficial. In our view, policymakers and program planners should consider adopting doses between 1.0 and 1.5 g elemental calcium/d, depending on the local average and variation in dietary calcium intake, logistical feasibility, and acceptability in the target population. Prudent practice would entail daily administration as calcium carbonate administered in divided doses of not >500 mg elemental calcium per dose. For ease of prescribing and adherence, calcium [as with iron and folic acid (IFA)] should be administered routinely to pregnant women from the earliest contact in pregnancy until delivery. Calcium’s acute inhibitory effect on iron absorption translates to minimal effects in clinical studies. Therefore, to simplify the regimen and facilitate adherence, providers should not counsel that calcium and IFA pills must be taken separately. Although further research will shed more light on clinical and programmatic issues, policies can be implemented with ongoing revision as we continue to learn what works to improve maternal and newborn health.