This thesis consists of a summary and four papers. The first two papers are theoretical contributions within the area of optimal taxation and public expenditures under asymmetric information between the government and the private sector, and the last two are empirical contributions to the literature on local public expenditures. Paper [I] concerns the optimal use of publicly provided private goods in an economy with equilibrium unemployment. The paper points out that imperfect competition in the labor market gives rise to additional policy incentives associated with the self-selection constraint, which motivates adjustments in the public provision of private goods. It also addresses employment related motives behind publicly provided privat...