Up to a tenth of the world’s population is affected by chronic kidney disease and over 2 million people are receiving dialysis or kidney transplantation. Even modest improvements in kidney size and function could generate substantial reductions in the development of end stage kidney disease. After donation of a kidney by a healthy individual or following nephrectomy for kidney cancer, the remaining kidney grows over the next few days and weeks and increases its function. This compensatory hypertrophy is dominated by an increase in size of individual kidney cells. The mechanism initiating the remaining kidney to naturally enlarge and increase its function in a healthy and enduring way has been elusive. We have utilised genomic and single cell techniques to identify pathways activated in the first few days after kidney removal.