The electronic structure of the ternary semiconductor alloys Hg1−xMnxSe, Cd1−xMnxSe, and Zn1−xMnxSe was examined through synchrotron radiation photoemission studies of single crystals cleaved in situ for 0≤x≤20%. Comparison with the parent binary compounds HgSe, CdSe, and ZnSe and resonant photoemission at the 3p–3d transition energy indicate that a Mn-derived density of states feature appears 3.5±0.1 eV below the valence band maximum and exhibits elemental 3d character with no evidence of important hybridization effects. The constant binding energy of the Mn 3d states in all of the compounds explored forces a reevaluation of existing models of bonding in ternary magnetic semiconductors.