Nearly 100,000 patients are waiting for a kidney transplant, yet each year only 11,000 undergo transplantation with a deceased donor kidney. Annual death rates among waitlist registrants range from 5% to 15%; many die before receiving a transplant. Not surprisingly, registrants turn to family and friends to become living kidney donors on their behalf. Living kidney donor selection practices aim to quantify lifetime risk for kidney failure based on a candidate's predonation demographic and health characteristics. It has been established that estimated lifetime risk for kidney failure varies considerably based on predonation comorbid conditions, and as such, it is of paramount importance that potential living donor candidates undergo proper medical, surgical, and psychosocial screening before donation. This installment of AJKD's Core Curriculum in Nephrology provides readers with the tools necessary for proper evaluation of living kidney donor candidates.