In recent years, the protection of genetic diversity within species has become a priority for conservation efforts. The long-term objective is to maintain the evolutionary viability of the taxon, maximizing its chances for persistence in the face of changing environments. Genetic considerations may also have short-term importance in our strategies for managing rare plants. When taxa have become critically endangered, and direct manipulations of field populations or the establishment of ex situ populations are being planned, what genetic factors should be considered? Here I review evidence concerning the relevance of genetic variation to the ecology and persistence of plant populations, with the goal of developing guidelines for the genetic management of rare plants.