The experience of childhood cancer is reported to be stressful for children with cancer and their families. Of special concern with respect to the consequences of cancer stressors is the issue of how cancer affects the child's sense of self. It has been suggested that the child's sense of self may be altered or potentially harmed by the effect of cancer and its treatment. Changes in the child's sense of self, in turn, may affect the child's quality of life. The purpose of this article is to examine what is known about the sense of self in children with cancer and in childhood cancer survivors. Additionally, conceptual and methodological concerns related to studying the sense of self in the pediatric oncology population are discussed. These include (1) conceptual blurring related to how the self is defined; (2) minimal theoretical grounding specific to understanding the self; and (3) limited research approaches to studying the self. Recommendations for research and practice that will lead to an increased understanding of the sense of self in this patient population are presented.