The study of exciton–longitudinal optical (LO) phonon coupling in semiconductor quantum well (QW) structures and their corresponding bulk materials reveals four distinct features: a large difference between (i) III-V and II-VI QW structures, (ii) multiple QW and single QW structures, as well as (iii) QW structures and their corresponding bulk materials, and its linear dependence on well width in QW structures. A quantitatively theoretical approach is presented, which can explain well all the experimental observations and can clarify the controversy in the literature. The effects of alloy disorder and strain in QW structures on exciton-LO phonon coupling are also discussed.