Abstract: Temperature-controllable reagent cartridges and systems for controlling the temperature in such reagent cartridges are provided. An example such system may include a reagent cartridge having reagent reservoirs located at least in part within an interior plenum volume of a cartridge housing. In such an example system, each reagent reservoir may be defined, in part, by a sidewall, and a first reagent reservoir may be spaced apart from a second reagent reservoir to form a fluid flow passage between corresponding sidewalls thereof. A fluid inlet through the cartridge housing may be provided that fluidically connects the interior plenum volume with a fluid supply port of a temperature control system of an analysis instrument when the reagent cartridge is received by the analysis instrument; a fluid outlet through the cartridge housing that fluidically connects the interior plenum volume with a fluid return port of the temperature control system may also be provided.