Detailed structure of spray flames has significant influence on burning rates, pollutant emissions, and flame stability. The purpose of the present study is to elucidate the ''group combustion'' structure of spray flames with or without gaseous fuel in terms of simultaneous monitoring and visualizing OH-radical chemiluminescence, CH- and/or C-2-band flame luminosity, and Mie scattering of droplet clusters and subclusters in the vicinity of an apparent flame front. It was found that, in the case of a small liquid fraction in the fuel and a small average diameter of droplets; gas-phase reaction occurred in premixed combustion mode inside the periphery of each droplet cluster, whereas in the case of a large liquid fraction in the fuel and a large average diameter of droplets, gas-phase reaction accompanied by OH-radical chemiluminescence occurred outside the periphery. In the latter case, the intense pulsating emission signals in the CH and/or C-2 bands that did not synchronize with the emission signal in the OH band were detected in the downstream region. This implies that small dense subclusters survived downstream of the flame front, burning with an intense solid-body light emission. These results suggest that the spray flame has a group structure-not a simple one, but a complicated one determined by the behavior of droplet clusters and subclusters.