A complete 4 × 4 diallel showed significant self-incompatibility and reciprocal differences in L. × ‘Mid-Century’ hybrid lily crosses. For all crosses, normal stigmatic pollination produced more seed set than did either intrastylar pollination method. For selfed flowers, intrastylar pollination methods generally resulted in more seed set but this was statistically nonsignificant. Significant reciprocal differences were found among crosses of ‘Harmony’, ‘Cinnabar’, and ‘Enchantment’ no reciprocal differences existed among ‘Joan Evans’ crosses. Seed set was highly correlated with pod width, length, and days to maturity.