This chapter aims to answer some of the questions: the steps involved in the generation of memory B cells, the functional B cell subsets, T cell requirements for memory B cell induction, and the clonal expansion of the memory B cell population. A rather extensive body of information on the site and kinetics of memory B cell development has accumulated. The memory B cells were originally characterized as predominantly long-lived small lymphocytes which arise within the follicular region of lymphoid tissue draining the site of antigen injection. In addition to the heterogeneity in the expression of membrane immunoglobulinD, there is great variation in the expression of membrane immunoglobulinM and membrane immunoglobulinG on memory B cells. The chapter outlines classical models of E. E. Sercarz and A. H. Coons for the generation of memory envisage a linear or branched pathway in which primary antibody-forming cell and memory cells arise from a common precursor.