The luminescence of inorganic ions, organic neutral molecules (or polyatomic anions or cations) incorporated in sol-gel glasses (formed during a programmed process by hydrolysis of alkoxides and subsequent polycondensation) usually gives higher (to far higher) yields than in low-viscosity water or alcohols. Photodegradation can be avoided in lasing perylimides dyes firmly fixed in the glass built up around them. Some quantum-chemical comments are made.