Post-transplant lymphoproliferative disorders (PTLDs) are a well-recognized complication of solid organ (SOT) and stem cell (SCT) transplantation. These lesions are highly variable based on morphology and clinical behavior. There are several risk factors associated with their development.1, 2, 3, 4, 5, 6, 7 However, it now recognized that these lesions, similar to lymphomas arising in immunocompetent individuals, may be different based on age. For example, some risk factors for developing PTLD are of more importance in younger patients, i.e. infants, children, adolescents (pediatric patients <18 years) and young adults (patients less than ≤30 years), than in older individuals and it may be that grouping patients into pediatric and adult cohorts is not sufficiently granular to adequately understand disease biology or appropriately treat patients. However, as this a new concept, it is difficult in the current literature to identify and characterize the PTLDs arising in adolescents and young adults. In many studies younger PTLD patients are often grouped with adults or are partitioned into groups based on inconsistent age ranges. Furthermore, many reports, whether on adults, younger patients (of variable age ranges) or all patients, are from individual institutions with specific immunosuppression and PTLD treatment protocols, are evaluating patients who have undergone a specific type of transplant or are investigating patients who developed PTLDs over long time periods (sometimes 20 years or more) during which immunosuppression protocols, PTLD treatment as well as PTLD diagnostic criteria and testing, have changed. For these reasons, understanding the biology of PTLDs arising specifically in adolescents and younger adult patients is difficult. However, as approximately 6000 of the 43,000 organ transplants performed in the United States in 2022 were in patients less than 34 years of age (https://unos.org), as PTLDs account for >85% of the malignancies in the post-transplant pediatric patient population (including adolescents) and as the highest risk for developing a PTLD is in males less than 18 years of age,8,9 our need to understand PTLDs in the younger population is imperative. In this review we will focus on solid organ transplant (SOT) related PTLDs unless otherwise noted.