Crop wild relatives (CWR) are plant species which are more or less closely related to crops. They are the repositories of genetic variation that can be used in breeding new and better adapted crop varieties that are resistant to stress, disease and more importantly the impact of climate change. The main conservation strategy adopted for CWR has been Ex situ. Now the need to conserve CWR in their natural surroundings (In situ) is increasingly recognized. Research coordinated by Bioversity International has produced a wealth of information on good practices and lessons learned for their effective conservation.