: In 1998, the US CDC announced the publication of a simple laboratory technique that would allow the differentiation of ‘recent’ from ‘longstanding’ HIV infections. Detection of recent infections with a laboratory test allows one to estimate HIV incidence using a cross-sectional survey. We believed the quest to be able to measure HIV incidence and monitor the epidemic in real time was over. How wrong we were! Eighteen years later we published a paper highlighting the incredible progress that has been made, but also outlined the many difficulties that remain.