Molecular prognostic and diagnostic tools allow for targeted cancer surveillance, prognostication, and treatment, and these assays have the potential to improve the lives of patients and their relatives. The impact of these advances, however, is not uniform across populations. Underserved communities frequently do not have the same level of access to novel assays, and the clinical application of these tools is often limited by disproportionate representation of White and European ancestry populations in foundational data, as well as limited diversity in clinical trials. In this review, we highlight major advances in clinical molecular assays, key areas of disparity, and contributing factors. We then list ongoing and future areas of intervention to improve access to and efficacy of molecular assays across populations, so that we as a community may work to improve equity at this critical area of cancer care.