This thesis is composed of three essays, and studies how monetary policy transmission is shaped by firm heterogeneity with particular focus on investment, borrowing, and pricing decisions. In the first chapter, Debt Contracts, Investment and Monetary Policy, I study the role of debt contracts on the transmission of monetary policy to firm-level investment and borrowing. Empirically, using information from a detailed loan-level data matched with balance sheet data and stock return data, I document that in response to a contractionary monetary shock, asset-based borrowers –firms with more pledgeable assets, and higher beta– experience sharper contraction in borrowing and investment than cash flow-based borrowers –firms with higher profitability and alpha. To explore the possible channels and provide microfoundation for the coexistence of these debt contracts, I setup a heterogeneous firm New Keynesian model with limited enforceability. The quantitative model suggests that the traditional collateral channel explains this heterogeneous sensitivity as the cash flow based borrowers are less susceptible to collateral damage from changes in asset prices. Results indicate debt contract type affects the severity of financial frictions and also shapes the monetary policy transmission. The second chapter, TFPR: Dispersion and Cyclicality, coauthored with Russell Cooper, studies the determinants of TFPR, a revenue based measure of total factor productivity. Recent business cycle models are built upon the assumption of countercyclical dispersion in TFPQ, a quantity based measure of total factor productivity, based on evidence of countercyclical dispersion in TFPR. But, these can be very different measures of productivity. The distribution of TFPR is endogenous, dependent upon exogenous shocks and the endogenous determination of prices. An overlapping generations model with monopolistic competition and state dependent pricing is constructed to study the factors that shape the TFPR distribution. The empirical focus is on three key data patterns: (i) countercyclical dispersion of TFPR, (ii) countercyclical dispersion of price changes and (iii) countercyclical frequency of price adjustment. The analysis uncovers two interesting scenarios in which these moments are matched. One arises in the presence of shocks to the dispersion of TFPQ along with a negatively correlated change in the mean of TFPQ. The second arises if the monetary authority responds to shocks to the dispersion of TFPQ by “leaning against the wind". Due to state contingent pricing, the model is nonlinear. Simple correlations mask these nonlinearities of the underlying economy. The real effects of monetary innovations are state dependent, with monetary policy less effective in recessions. In the third chapter, Sectoral Volatility and the Investment Channel of Monetary Policy, written jointly with Thomas Walsh, we investigate how the dispersion of firm-level shocks affect the investment channel of monetary policy. Using firm-level panel data, we construct several measures of dispersion of productivity shocks, time-pooled and timevarying, and interact high-frequency identified monetary policy shocks with these measures of idiosyncratic shock volatility. We document a novel fact: monetary policy has dampened real effects via the investment channel when firm-level TFP shock volatility is high. Our estimates for dampening effects of volatility are statistically and economically significant - moving from the tenth to the ninetieth percentile of the volatility distribution approximately halves point estimates of impulse response functions to contractionary monetary policy shocks. Given that dispersion rises in recessions, these findings offer further evidence as to why monetary policy is weaker in recessions, and emphasize the importance of firm heterogeneity in monetary policy transmission.