This thesis is comprised of three essays. The first two investigate the relationship between monetary policy power and the prevalence of earmarked credit (featuring interest rates that are insensitive to the monetary cycle) in the economy. The first shows that the available microeconometric evidence is not necessarily informative about the macroeconomic phenomenon of interest, and illustrates this result with a simples New-Keynesian model with working capital credit. Giving sequence, the second essay extends the analysis with a medium-sized DSGE model where earmarked credit is used to finance the acquisition of physical capital by firms. The model is estimated to Brazil using Bayesian techniques. Under the prior distribution it is shown that the presence of earmarked credit does not necessarily reduces monetary policy power over inflation. Under the posterior it is shown that a reduction of power is likely, but small. Finally, the third essay studies to what extent the effects of capital flows on a small open economy s business cycle depend on the type of the inflow (e.g., whether a bond or a stock inflow, a liability or an asset flow), and for such it build an open economy New-Keynesian model with financial frictions. Direct mechanisms through which inflows may have differentiated effects depending or their type are identified. Using a calibrated version of the model it concludes that the differences are probably of little significance.