The purpose of this study was to develop and test three instruments to measure fatigue in children with cancer from the perspectives of the child, parents and staff. The study consisted of three phases: instrument development, content validation, and estimations of psychometric properties of the three fatigue instruments. One hundred forty-nine children between the ages of 7–12 years presently receiving chemotherapy for cancer, 147 parents and 124 staff participated in this study. The instruments demonstrated strong initial validity and reliability estimates. This study is the first to provide valid and reliable instruments to measure fatigue in children with cancer.