In my dissertation, I studied Social Choice and Fair Division problems under uncertainty. In the first chapter, I defined welfare egalitarianism in the form of certainty equivalence where the individuals are endowed with state contingent consumption bundles and provided an axiomatic characterization of this ordering by efficiency, equity and monotonicity axioms. In the second chapter, I defined two proportional rules on the rationing problem with state contingent claims and gave the characterization of those two rules by No Advantageous Reallocation. And in the last chapter, I consider a class of resolute social choice correspondences and characterize the strong Nash equilibrium outcomes of their voting games in terms of a generalization of the Condorcet principle.