Luminescent silver clusters stabilized in different hosts represent an important class of new luminophores with numerous potential applications. Nevertheless, there are a lot of open questions regarding the emission mechanism of the clusters. In this work, luminescence properties of silver clusters in a silica-based glass were analyzed by using steady-state and time-resolved spectroscopy. The obtained results suggest that deactivation of cluster excited states does not include cluster interaction and should be treated on a single cluster scale. The temperature change of cluster emission confirms the mechanism of temperature-activated intersystem crossing as a way of excited singlet state deactivation. The study of fluorescence temperature dependence reveals the features attributed to the existence of two different temperature-activated quenching processes.