The paper begins with a brief description of the energy demand distribution within Thailand showing the extent of chronological and geographical variations. The effects of the slow down of the economy on forward planning and the resulting generation reserve margins are also described. Having set the background of the demands on Thailand's Electricity Supply Industry a comprehensive picture of it's present structure is given. This shows an Industry dominated by. three state owned enterprises, one undertaking Generation and Transmission the other two responsible for Distribution and Retail. The paper does, however, describe an established and growing privately owned sector in the Generation Business.