The polarity dependent fluorescence, quantum yields and lifetimes at room temperature have been measured for two squaraine dyes, SQ-DMA and its crown ether derivative SQ-CR. The unstructured fluorescence bands and the polarity independent kf values indicate fluorescence from one single species. The nonradiative decay rates increase strongly with solvent polarity, indicating a polarity-induced intramolecular fluorescence quenching process. The latter could be due to the formation of a nonemissive twisted intramolecular charge transfer (TICT) state. Low-temperature measurements and the comparison of SQ-DMA and SQ-CR support this view.