Cardiotoxicity has historically been a major cause of drug removal from the pharmaceutical market. Several chemotherapeutic compounds have been noted for their propensities to induce dangerous cardiac-specific side effects such as arrhythmias or cardiomyocyte apoptosis. However, improved preclinical screening methodologies have enabled cardiotoxic compounds to be identified earlier in the drug development pipeline. Human induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) can be used to screen for drug-induced alterations in cardiac cellular contractility, electrophysiology, and viability. We previously established a novel ‘cardiac safety index’ (CSI) as a metric that can evaluate potential cardiotoxic drugs via high-throughput screening of hiPSC-CMs. This metric quantitatively examines drug-induced alterations in CM function, using several in vitro readouts, and normalizes the resulting toxicity values to the in vivo maximum drug blood plasma concentration seen in preclinical or clinical pharmacokinetic models. In this ~1-month-long protocol, we describe how to differentiate hiPSCs into hiPSC-CMs and subsequently implement contractility and cytotoxicity assays that can evaluate drug-induced cardiotoxicity in hiPSC-CMs. We also describe how to carry out the calculations needed to generate the CSI metric from these quantitative toxicity measurements.