Personalized medicines hold promise for many diseases. However, demonstrating the clinical efficacy and cost effectiveness of these medicines can be difficult. It is essential that decision-making processes for funding new medicines, including personalized medicines, are both robust and fit for purpose. We will argue that randomized trials of personalized medicines should be routinely supplemented with other research methods, such as observational research and single-arm studies, and that managed-entry funding programs, such as coverage with evidence development, may offer a means of providing early access to technologies where there is uncertainty about efficacy, safety, and cost effectiveness. These programs, however, raise a number of practical and ethical challenges that need to be worked through and resolved.