This first and final report of the ONE Foundation sets out the story of ONE over it's ten-year lifespan. Section 2 describes the key decisions that shaped ONE and how these unfolded over time. Section 3 outlines the goals, strategies and outcomes of the four programmes we chose to invest in, and highlights what we believe was achieved through our funds and efforts. Section 4 gives examples of initiatives we undertook that didn't seem to fit in, and yet played an important role in the end. Section 5 describes what we did to plan for and support exit from long-term grantees during difficult economic times. Perhaps most importantly, section 6 outlines the lessons we learned. We are happy to share what we believe were the key drivers of our successes (and failures) so that the next generation of philanthropists and social changemakers can benefit from our experience. Section 7 sums up ONE's legacy, if there is one. We can hardly ever agree on that at ONE.