Flash memory devices and methods of programming the same are provided. The flash memory devices include a plurality of memory cells storing multi-bit data representing at least one of first through fourth states and including most significant bits and least significant bits. The method includes programming the plural memory cells into a provisional state according to the least significant bit, and programming the plurality of memory cells into the second through fourth states from the first and provisional states according to the most significant bit. Programming the plurality of memory cells into the second through fourth states includes simultaneously programming the plurality of memory cells at least partially into at least two states during one programming operation period.