Tunable laser emission from 3850 to 5740 Å has been observed from three solvate forms of 4‐Methylumbelliferone. The three distinct lasing forms basic, neutral, and acid, with tuning ranges of 1070, 720, and 1150 Å, respectively, were obtained by adjusting the solvent pH. A tuning range of 1760 Å (from 3910 to 5670 Å) has been obtained in a critically adjusted, slightly acidic solution. The various chemical structures responsible for the broad tuning have been identified. Evidence that the acid form lases from an exciplex (excited complex) state is presented.