Non-Hodgkin's Lymphoma (NHL) is defined as any of a large group of cancers of the immune system. NHL's can occur at any age and patients are often marked by enlarged lymph nodes, fever, and weight loss. There are many different types of non-Hodgkin lymphoma, which can be divided into aggressive (fast-growing) and indolent (slow-growing) types and can be classified as either B-cell or T-cell non-Hodgkin lymphoma. The guest editor has provided a thorough overview of this topic by having expert clinicians write about the diagnosis and management of follicular lymphomas, marginal zone lymphomas, B-cell lymphomas, cutaneous T-cell lymphomas, and peripheral T-cell lymphomas. State-of-the-art treatments are discussed, including novel chemotherapeutic agents, new biological agents, and immunologic strategies.