The outcomes in young adults aged 20-39 with sarcoma tend to be inferior compared to those in children and adolescents. There are differences in sarcoma histotype distribution with age, such that pediatric-type tumors predominate in the 20- to 25-year-old group while more adult-type sarcomas occur in those aged 35-39 years. Certain occupational exposures, co-infection with human herpes virus 8 (HHV-8) and human immunodeficiency virus (HIV), prior radiation exposure, and genetic syndromes are relevant risk factors. In many of the types of sarcoma encountered in 20 to 39 year olds, there are important biological differences compared to the tumors in younger patients that play a role in the outcomes for these patients. Increased research into these differences and incorporating our knowledge about them into treatments tailored towards this age group is necessary to overcome the relatively poor outcomes in young adult sarcoma patients.