Abstract The clearance and control of many intracellular pathogens and tumors rely on the development of efficacious CD8 T cell responses. These responses are functionally diverse, however, whether and how this heterogeneity forecasts effector formation, memory potential, and protective capacity has not yet been definitively determined. To address this, we utilized IL-2 and IFN-γ double cytokine reporter mice to separate viable IL-2 and IFN-γ producing CD8 T cell subsets, and performed a series of adoptive transfer experiments to track their memory potential and fate. We discovered that within hours of activation, naïve CD8 T cells undergo a burst of cytokine synthesis and distinct populations develop that produce only IL-2, only IFN-γ, co-produce IL-2 and IFN-γ, or do not produce either cytokine. This diversity is consequential as newly activated naïve CD8 T cells that fail to produce IL-2 preferentially attain effector features. Conversely, autocrine IL-2 production by recently activated naïve CD8 T cells is associated with the formation of memory traits. Similarly, the ability of CD8 T cells to produce IL-2 during the effector phase also signified memory potential and the ability to mount vigorous secondary proliferative responses. Together these data demonstrate that functional heterogeneity influences the differentiation of CD8 T cell responses and that effector and memory formation can be predicted by the pattern of autocrine IL-2 production.