Organic molecules with a strong preference for triplet ground states, in which the triplet state is below the lowest singlet state by >= 10 kcal/mol, are typically short-lived and mostly detected as reactive intermediates. We now report a triplet ground state derivative of aza-m-xylylene diradical with a large singlet-triplet energy gap (Delta E-ST) of similar to 10 kcal/mol, which is comparable to Delta E-ST for the well-known reactive intermediate m-xylylene diradical. The aminyl diradical persists in solution at room temperature on the time scale of minutes.