Commercialization is the process of bringing diagnostics from the laboratory setting to the commercial market. Rapid Acceleration of Diagnostics (RADx®) portfolio companies were tasked with developing and producing millions of rapid, accurate, low-cost, and convenient COVID-19 tests to meet surging demand, but tests only help if people can access them. Many would-be purchasers discovered that tests alone would not solve the problem – they needed comprehensive testing solutions. In this chapter, we discuss RADx’s role in assisting portfolio companies in understanding customers’ evolving needs; the shifting market dynamics with each new wave, vaccine, or variant; and the barriers and opportunities to market success. We highlight go-to-market strategies and policy decisions that worked well and we outline policy and regulatory barriers that hindered broader success. We reflect on the lessons learned and potential solutions to adopt before the next pandemic and in the broader context of the future diagnostic delivery system.