Economic recovery for a steam-stimulated well seems to be high in the immediate vicinity of the well bore, decreasing further away. Therefore, overall recovery efficiency could be increased with decreasing well spacing. The hypothetical optimum spacing for a field or lease can be calculated analytically based on maximum present worth of profit if good estimates of recovery, productivity, decline, and economic cost data are available. Analytical estimates of recoverable reserves in some selected specific areas under steam stimulation indicate that dense drilling spacing may be economically justified. The increasing price per barrel of oil may support denser drilling in areas where further development could not previously be justified economically. The use of multiple-well drilling programs may be used to assess properly the attractiveness of further development by statistically valid observations. Optimum spacing may be shown to vary within a lease, with denser drilling indicated in the thicker sand portions where higher recovery per acre can be expected, or in the structurally lower locations that receive the greatest benefit from the effects of gravity drainage. (17 refs.)