This article describes research related to the design of a payment model for specialty oncology services for possible testing by the Center for Medicare and Medicaid Innovation at the Centers for Medicare & Medicaid Services (CMS). Cancer is a common and costly condition. Episode-based payment, which aims to create incentives for high-quality, low-cost care, has been identified as a promising alternative payment model for oncology care. Episode-based payment systems can provide flexibility to health care providers to select among the most effective and efficient treatment alternatives, including activities that are not currently reimbursed under Medicare payment policies. However, the model design also needs to ensure that high-quality care is delivered and that beneficial treatments are not withheld from patients. CMS asked MITRE and RAND to conduct analyses to inform design decisions related to an episode-based oncology model for Medicare beneficiaries undergoing chemotherapy treatment for cancer. In particular, this study focuses on analyses of Medicare claims data related to the definition of the initiation of an episode of chemotherapy, patterns of spending during and surrounding episodes of chemotherapy, and attribution of episodes of chemotherapy to physician practices. We found that the time between the primary cancer diagnosis and chemotherapy initiation varied widely across patients, ranging from one day to over seven years, with a median of 2.4 months. The average level of total monthly payments varied considerably across cancers, with the highest spending peak of $9,972 for lymphoma, and peaks of $3,109 for breast cancer and $2,135 for prostate cancer.