MicroRNAs (miRNAs) play important roles in development, differentiation, homeostasis, and also in diseases such as lymphoma. This chapter describes methods to study the role of miRNAs in lymphoma. First, we describe a multiplex RT reaction followed by qPCR that can be used to determine differential expression of candidate miRNAs. Second, we provide a protocol for stable overexpression of miRNAs using lentiviral-based ectopic expression systems. Third, we describe a straightforward assay to determine whether the candidate miRNA may function as an oncogene or a tumor suppressor gene in lymphomagenesis.