In the United States, 1 of approximately every 285 children will be diagnosed with cancer before the age of 20 years. Although relatively rare, childhood cancer is the leading cause of disease-related deaths in children and adolescents. Understanding the epidemiology of childhood cancer is imperative for progress to be made in the diagnosis, treatment, and cure of childhood cancer. This chapter will include a discussion of pediatric cancer incidence by age and cancer type, gender, and race/ethnicity as well as trends in pediatric cancer incidence over time. Mortality and survival rates for pediatric cancer will also be discussed. In addition, the chapter will explore the possible causes of pediatric cancer, including both extrinsic and intrinsic risk factors. This chapter focuses on the descriptive epidemiology of childhood cancer as well as discussing the possible causes of childhood cancer with the hopes of providing a basic understanding to the reader of the epidemiology of childhood cancer.