More and more firms today have to cope with the challenge of combining mass customization and green management, but research on green mass customization is still limited. To narrow this gap, we empirically investigate whether complementarities between organizational capabilities supporting mass customization (MCCs) and organizational capabilities supporting green management (GMCs) exist and why. Based on an in-depth longitudinal case study, we posit four either symmetric or asymmetric complementarities between specific pairs of MCCs and GMCs. These findings suggest synergies that companies faced with the twofold challenge of MC and GM may leverage to reduce the costs of that challenge.