Arabidopsis thaliana is a wild species widely distributed in diverse environments and current resources allow efficient quantitative analyses aimed to identify the genetic and molecular bases of adaptation. The study of natural genetic variation in this model plant has rapidly developed in the past 10 years, leading to the identification of hundreds of loci that are responsible for the variation of a plethora of traits and more than 30 of the underlying genes. This knowledge can be used for the identification of genes also relevant for crop breeding. Particularly, related species of A. thaliana such as Brassica sp. may benefit from this information because current genomic information is providing detailed knowledge of genetic synteny among these species. In this chapter, we summarize the approaches that are followed to dissect A. thaliana intraspecific variation. In addition, the main results obtained up to now are described considering current possibilities to transfer them to Brassica crops.