With the discovery of Co-based superalloys exhibiting γ/γ’ morphologies, a flurry of research has been performed to determine their high-temperature strength and the effect of alloying on γ’ phase stability. However, fundamental properties for the base Co3(Al,W) L12 γ’ remain unknown. We have previously explored with DFT the stability of γ’ and found that at low temperatures, γ’ is a thermodynamically metastable phase. At higher temperatures, entropy-driven effects may potentially stabilize the structure. We have now performed DFT calculations on a fundamental thermodynamic quantity that influences the high-temperature yield strength anomaly, the antiphase boundary (APB) energy. The 100 and 111 APB energies are predicted for Co3(Al,W) L12 γ’ and some observations are made as to the unique nature of Co3(Al,W) L12 compared to the more commonly studied Ni3Al. We also predict the effect of a variety of solutes on APB energetics.