This paper identifies distinctive regimes for the combustion of particles in a packed bed. The study is based on the relevant time and length scales for combustion and transport in both the solid fuel and the gas phase within the voids in a packed bed. Characterizing the combustion of a particle and a packed bed by the dimensionless groups, the Damkohler number, and the Thiele modulus, four different combustion regimes are identified. Two of them resemble the well-stirred reactor with uniform reaction throughout the packed bed, whereas the particles may follow the kinetically or transport-limited reaction path. For the remaining regimes a conversion front propagates with its characteristic velocity through the packed bed, independent of whether the combustion of particles within the conversion front follows the reacting or the shrinking core mode.