Researchers have paid little attention to examining how non-Chief Executive Officer (CEO) board chairs' corporate governance approaches impact firms' acquisition outcomes.Non-CEO board chairs use distinct approaches to manage their working relationships with the CEO, characterised as control and/or collaborative approaches.Drawing on cognitive learning theory, we posit that these approaches may have unique effects on firms' acquisition intensity and post-acquisition performance.Using a sample of 163 distinct Standard & Poor's (S&P) 500 companies that completed 759 acquisitions, we found that both control and collaboration approaches lead to increases in acquisition intensity.However, the control approach negatively influenced performance, whereas collaboration had little impact on performance.This study provides further evidence that how board chairs approach corporate governance and their working relationship with the CEO have implications for firms' strategic actions and performance.