We study how congressional testimony about monetary policy by the Chair of the Board of Governors of the Federal Reserve System affects interest rates and stock prices. First, we study testimony associated with the Federal Reserve’s Monetary Policy Reports (MPRs) to Congress. Testimony for a particular MPR is usually given on two days, one day for each chamber of Congress. We separately study the first day and second day of MPR testimony. We also study testimonies not associated with MPRs but that are still related to monetary policy. We find that first-day MPR testimonies cause the largest movements in interest rates and generate negative co-movement between interest rates and stock prices. Testimonies not associated with MPRs have similar but weaker effects. Second-day MPR testimonies cause the smallest movements in interest rates and generate no co-movement between interest rates and stock prices. •How does Federal Reserve Chair testimony affect interest rates and stock prices?•Different types of testimony matter for the magnitude of effects.•First-day Monetary Policy Report testimonies have the largest effects.•Forward guidance in testimony explains little of the movement in stock prices.•We make our data publicly available for other researchers.