This paper studies market liquidity in interest rate swaps before and during the global tightening of monetary policy starting in June 2022. Interest rate swaps constitute the single largest derivatives segment globally and account for a large share of centrally cleared instruments. Banks and pension funds rely extensively on interest rate swaps to hedge interest rate risk. Hence, understanding this market and the drivers of market liquidity is a key research problem in the current market context. We use price and volume data from around 338 000 centrally cleared trades in the most active long-horizon swap contract denominated in euros to construct seven liquidity measures. Taking a comprehensive approach, we apply linear regressions to determine the drivers of variation in liquidity. Our liquidity measures are significantly related to monetary policy, market-wide fixed-income liquidity, Euro Interbank Offered Rate volatility and dealer behavior.