This thesis deals with the problems of optimal grading, employee performance evaluation by unaccountable managers, and the evolution of inequity-averse preferences. The purpose is to explain certain stylized facts related to these problems, and this is attempted with the help of contract-theoretic models. Chapter 1 of this thesis studies a teacher-student relationship as a principal-agent model with a costless reward structure. The model shows that the stylized fact of a mismatch and low correlation between students' abilities and their grades can be the expected-effort-maximizing outcome of teachers' optimal grading. Chapter 2 presents a three-tier model of a firm's economic organization, which is centered on the observation that managers do not fully internalize the payroll expenses they incur. With the idea that the degree of manager accountability varies inversely with firm size, the model predicts that the compression of ratings, the large-firm wage premium, and the inverse relationship between wage dispersion and firm size can actually be equilibrium outcomes. The last chapter presents an evolutionary argument for the endogeneity of people's preferences with respect to market exposure. It shows that aversion to income inequality observed empirically could have evolved as an optimal response to merchants' price discrimination. / <p>Diss. Stockholm : Handelshögskolan, 2009</p>