Beyrer C et al. – The authors sought to review the recent epidemiology of HIV–1 and to identify emerging challenges in HIV surveillance and epidemic control. There is increasing evidence that HIV epidemics are in decline among general populations worldwide. Critical exceptions to these trends are HIV epidemics among key populations globally; the HIV epidemics in Eastern Europe and Central Asia in injecting drug using populations; the continued high burden epidemics of sexually transmitted HIV among young women and girls in southern sub–Saharan Africa, and young men who have sex in men (MSM) in the America, Asia, and Africa. In the new era of ART access, prevalence measures over time are less reliable and new approaches to the measurement of incident infection will be critical to assess trends. The epidemiology of HIV infection is changing, dynamic, complex, and progress in epidemic control remains markedly uneven. Without addressing the components of global HIV, in which disease rates continue to expand, current efforts are unlikely to succeed.