University of Minnesota Ph.D. dissertation. June 2014. Major: Economics. Advisor: Timothy J. Kehoe. i computer file (PDF); xi, 132 pages.In the first essay I develop a quantitative framework of firm dynamics where the size of the informal sector is determined by financial constraints and government taxation. Informal sector firms do not pay taxes but have no access to external finance. For taxes and financial constraints parameterized for a country like Egypt, I find losses in total factor productivity of over 28% and in output per worker of 60% relative to the US benchmark. The effects of the elimination of formal sector registration costs are small. Improving the access to credit for formal sector firms increases wages, aggregate TFP and ...