Kalasin (Thai: กาฬสินธุ์, pronounced [kāːlāsǐn]) is one of the northeast (Isan) provinces (changwat) of Thailand. The province was established by the Act Establishing Changwat Kalasin, BE 2490 (1947), which came into existence as 1 October 1947.
Neighboring provinces are (from north clockwise) Sakon Nakhon, Mukdahan, Roi Et, Maha Sarakham, Khon Kaen, and Udon Thani.