The article highlights a new study on t-cell development. According to the author, α&#x03B2 and γδ T cells have distinct functions and reside in different locations yet they originate from a common precursor in the thymus. The new study identifies SOX13 as a γδ-lineage-specific transcription factor that seems to function as a switch to control γδ- versus αβ-T-cell development, in part, by controlling T-cell factor 1 activity.