All cancers arise from complex interactions between aspects of the patient (host) biology and the environment. Once tumors arise, they frequently remain dependent on interactions with their microenvironment for their growth and proliferation. In this review, we examine the contributions of the host genetics and environmental exposures to the development of lymphoma. We will further examine the interactions of the tumor and the microenvironment that influence tumor growth and proliferation.Most tumor cells cannot survive for long when taken outside their immediate environment. This indicates a level of dependence on secreted factors or direct cellular interactions with the microenvironment that provides survival signals. This dependence may arise from normal interactions of the normal cell counterpart or it might arise from new, abnormal interactions that arise from the tumor biology. The precancer host biology itself may have a role in either promoting tumor growth or permissive growth by either harboring polymorphisms that, in the right context, promote tumor growth, or through behaviors that increase exposure to elements that promote carcinogenesis.Emerging technologies have provided new insights into the biology of a number of lymphomas. These technologies include microarrays that have enabled gene expression profiling to define the role of malignant and nonmalignant cells in the biology of lymphomas.Herein, we review the known contribution of the tumor microenvironment and host biology to the risk of developing lymphoma and the role of inherited and acquired host factors in disease progression and prognosis in patients with lymphoma. We will examine the tumor "macro" environment (ie, the biology of the patient [host]) and the tumor "micro" environment that contribute to the observed malignant phenotype.