Robust immunity to intracellular infections is mediated by antigen-specific naive CD8 T cells that become activated and differentiate into phenotypically and functionally diverse subsets of effector cells, some of which terminally differentiate and others that give rise to memory cells that provide long-lived protection. This developmental system is an outstanding model with which to elucidate how regulation of chromatin structure and transcriptional control establish gene expression programs that govern cell fate determination, insights from which are likely to be useful for informing the design of immunotherapeutic approaches to engineer durable immunity to infections and tumors. A unifying framework that describes how naive CD8 T cells develop into memory cells is still outstanding. We propose a model that incorporates a common early linear path followed by divergent paths that slowly lose capacity to interconvert and discuss classical and contemporary observations that support these notions, focusing on insights from transcriptional control and chromatin regulation.