The ChaMP Research Network has reviewed evidence on the transmission of monetary policy to firms in the euro area. The transmission of monetary policy to firms remains effective, even during the 2022-23 tightening cycle. However, the transmission is not uniform and is influenced by multiple factors, including country-level segmentation and bank balance sheets. Sovereign risk, institutional frameworks, and local lending practices also play a role in shaping transmission, particularly during periods of stress. The composition of banks' liabilities can affect the speed of transmission, leading to different outcomes. Firm characteristics, such as funding mix, also impact the effect of monetary policy on individual firms. At the contract level, factors like collateralisation and interest rate fixation can influence the magnitude and composition of transmission. The heterogeneities in transmission can have aggregate implications in certain circumstances. To address these complexities, a broad and flexible toolkit is necessary to ensure effective monetary policy transmission. This toolkit can include the main policy rate, asset purchases, and targeted liquidity operations, which can be deployed in a proportionate manner to accommodate the diverse needs of the monetary union.