Research was conducted to determine appropriate in-row spacing for eggplant ( Solanum melongena ) and to determine the best economic returns of this practice. ‘Classic’ eggplant seedlings were transplanted at in-row distances of 1.0, 1.5, 2.0, 2.5, 3.0, and 3.5 ft. Eggplant height decreased linearly as in-row spacing increased. In-row spacing affected total eggplant fruit number, with no fruit number differences among 1.0, 1.5, 2.0, and 2.5 ft, averaging ≈46,800 fruit/acre. Total fruit weight followed a trend similar to that for total fruit number and there were no differences among 1.0, 1.5, 2.0, and 2.5 ft (ranging between 18.2 and 19.9 tons/acre). From an economical standpoint, the comparison between 2.0 and 2.5 ft resulted in the former spacing having a marginal return rate of 8.03% in relation to an in-row spacing of 2.5 ft, which indicated that growers would earn $0.08 extra for each $1.00 of net profit by switching from 2.5 to 2.0 ft in-row plant spacing.