Lymphoid tissue inducer (LTi) cells are required for lymph node formation during fetal development, and recent evidence implies a role in mucosal immunity in the adult. LTi cells share some phenotypic features of conventional natural killer (NK; cNK) cells; however, little is known to date about the relationship between these two cell types. We show that lineage⁻ (Lin⁻) CD127⁺RORC⁺ LTi-like cells in human tonsil are precursors to CD56⁺CD127⁺RORC⁺NKp46⁺ cells, which together comprise a stable RORC⁺ lineage. We find that LTi-like cells and their CD56⁺ progeny can be expanded and cloned ex vivo without loss of function and without conversion into cNK cells. Clonal analysis reveals heterogeneity of cytokine production within the CD127⁺ LTi-like population. Furthermore, we identify within the tonsil a cNK precursor population that is characterized as Lin⁻CD117⁺CD161⁺CD127⁻ cells. Overall, we propose that CD127⁺RORC⁺ cells, although they share some characteristics with cNK cells, represent a functionally and developmentally distinct lineage.