Results/Conclusions: The model analysis indicates that if complete outcrossing is selected, pollen limitation increases seed size. The optimal seed size maximizes the ratio of juvenile survival rate to the resource investment needed to produce one seed (including both ovule production and seed provisioning), that is, the optimum maximizes the fitness effect per unit cost. Seed size determines resource allocation to post-breeding adult survival, and an increased seed size under pollen limitation increases post-breeding adult survival rate. Mixed mating is selected (i.e., producing selfed seeds to provide reproductive assurance) only when the size of outcrossed seeds and adult survival have increased to a certain extent such that resource investment in an outcrossed seed, adult survival, or a selfed seed produces equal marginal fitness returns. In such cases, outcrossed seeds should be larger than selfed seeds, and because pollen limitation does not affect the size of selfed seeds, pollen limitation should not affect the size of outcrossed seeds and adult survival. Moderate pollen limitation, strong inbreeding depression, and cheap cost of ovule production tend to select for complete outcrossing, while the reverse tend to select for mixed mating or complete selfing. The effect of pollen limitation on the selection of seed size and self-fertilization also applies to semelparous plants.