We calculate the mean number of subjets in quark and gluon jets in the final state of e +e − annihilation. Since “quark” and “gluon” jets are scheme-dependent objects, we stress the importance of using the same definition as in experimental analyses. We define the jets using the k ⊥ algorithm at a coarse scale y 1, and the subjets using a finer scale y 0, in the s algorithm. Gluon jets are anti-tagged by the presence of heavy quarks in both other jets. Our result is exact to leading order in α s, and resums leading and next-to-leading logarithmic terms in the ratio y 1 y 0 to all orders in α s.