In recent years the New Keynesian framework has become widely used to identify the relationship between monetary policy, inflation, the business cycle and welfare. Most commonly in these models inertia in prices are introduced only through the aggregate supply side which generates a short run non-neutrality of money. This thesis begins with an investigation into the impact of sticky prices on the macroeconomic equilibrium through aggregate demand. We show that in models of price stickiness among differentiated goods aggregate consumption deviates from the conventional Euler equation due to relative price distortions. This has some non-negligible implications: there are additional inflation effects, which enter through aggregate demand, that lower the response of the marginal cost and dampen responses of inflation and output; products' price elasticity of demand affects equilibrium output and inflation dynamics independently of supply factors; monetary policy responses are smoother than in the conventional new Keynesian models, particularly the more competitive are the products markets. In chapter 2 we continue with an investigation into the impact that the aforementioned channel has on welfare and monetary policy under various regimes. Specifically, we compare our results with the benchmark New Keynesian model with a cost channel for alternative levels of competition in the goods market. When the central bank is assumed to follow a Taylor rule we find, contrary to the standard New Keynesian literature, that welfare losses ultimately fall as the goods market becomes more competitive. Furthermore, there are additional adverse implications for welfare coming through an exaggerated stabilisation bias associated with discretionary policy in our model version. A move to optimal commitment implies significant additional gains compared to the standard literature by; eliminating this amplified stabilisation bias and; reducing further the fall in output gap and inflation fluctuations at the time of shock. The final part of this thesis develops a Generalised Taylor economy to include a financial market. This finance sector is characterised by savings contracts to households and loan contracts to firms, both of which are differentiated by the duration for which their interest rate remains fixed. Additionally, a time varying external finance premium on loan rates is introduced through an endogenous probability of firm default. Using break-even conditions we show that the fixed markup on loan rates is dependent on, the expected default risk over the lifetime of the contract, and, spillovers from the unexpected losses of current "locked in" financial contracts that must be accounted for in the zero profit condition of the commercial bank. Our results indicate that inertia in loan and savings rates dampens the responses of monetary policy and the business cycle whilst generating a procylical loan rate spread. In contrast, risk of default amplifies the business cycle and delivers a countercyclical loan rate spread. The overall impact of these two channels on the direction and magnitude of loan rate spreads, spillovers to new contracts and the dynamics of the business cycle, are shown depend on the type of shock hitting the economy.