Many individuals perform cell viability assays as a measure of biocompatibility whether the focus of their research is on novel drug discovery, development of novel biomedical devices, or the study of biointerfacial phenomena. In this tutorial paper, the most commonly used methods available to users to perform biocompatibility testing are discussed. This includes a brief introduction into the benefits and drawbacks of the techniques, including which are best used as screening assays, which are better suited to experienced users, the relative cost of the assays per unit, and what detection techniques are most appropriate for use in conjunction with the assays. In addition to helping users ensure the rigor and reproducibility of their research design, this tutorial is meant to assist reviewers of interdisciplinary journals (such as Biointerphases itself), whose expertise is in other areas of this research but do not have the experience with cell-based assays themselves.