Citrus is a leading fruit crop worldwide, with more than 130 million tons and mandarins representing 25% of total production. Mandarins are destined mainly to the fresh market, with China and the Mediterranean region being the main areas of production. Mandarins are a diverse group showing high genetic variability, thus allowing the development of efficient breeding programs based on both mutation and hybridization schemes. This chapter highlights recent advances in genetics, genomics and the biotechnology of mandarins. In addition, a case study is described for improving sustainability in mandarin cultivation through triploid breeding for seedlessness and marker-assisted selection for disease resistance.