This chapter discusses the properties (band-gap energy, exciton binding energy, and lattice constant) of ZnO and (Zn,Cd)O quantum wells. Recent progress in the epitaxial growth of ZnO and (Cd,Zn)O has led to the growth of ZnO-related quantum-well structures. ZnO alloyed with Mn, Co, Ni, show the properties of diluted magnetic semiconductors, while this is not the case when Sc, Ti, V, or Cr is incorporated. The nature of band-gap near emission bands in ZnO quantum wells is typically attributed to be of excitonic nature. Low-temperature photoluminescence (PL) and photoluminescence excitation (PLE) spectra from ZnO/Zn0.8Mg0.2O multiple quantum wells are shown. A theoretical treatment of the exciton transition energy and binding energy suggests that the interaction between electron and hole is polaron-like at large distances but approaches the dynamically screened Coulomb interaction as the separation is reduced. First and second order LO-phonon sidebands of both bound and localized excitons can be observed in photoluminescence. The exciton-LO phonon coupling is found to be reduced with respect to bulk ZnO in quantum wells where the exciton binding energy exceeds the LO-phonon energy. Biexcitons, excitonic gain and lasing, dynamics of optical excitations are discussed under the intermediate-density regime.