The fusion-evaporation reaction 1 0 B( 1 2 C,2n) was used to make the first observation of in-beam γ decays from the astrophysically important nucleus 2 0 Na, lying adjacent to the proton drip-line. All states below the proton threshold in 2 0 Na were populated and identified in the experiment. These include new levels, previously unresolved levels, and states located with improved energy precision. The level structure of 2 0 Na, and its γ transitions, are compared to the mirror partner 2 0 F measured simultaneously in this experiment. In particular, a high degree of energy stability is found for all negative parity states. These results are discussed in the context of the nuclear shell model.