  SuperNEMO is a double-$\beta$ decay experiment, which will employ the
successful tracker-calorimeter technique used in the recently completed NEMO-3
experiment. SuperNEMO will implement 100 kg of double-$\beta$ decay isotope,
reaching a sensitivity to the neutrinoless double-$\beta$ decay
($0\nu\beta\beta$) half-life of the order of $10^{26}$ yr, corresponding to a
Majorana neutrino mass of 50-100 meV. One of the main goals and challenges of
the SuperNEMO detector development programme has been to reach a calorimeter
energy resolution, $\Delta$E/E, around 3%/$sqrt(E)$(MeV) $\sigma$, or
7%/$sqrt(E)$(MeV) FWHM (full width at half maximum), using a calorimeter
composed of large volume plastic scintillator blocks coupled to photomultiplier
tubes. We describe the R\&D programme and the final design of the SuperNEMO
calorimeter that has met this challenging goal.
