Purpose: This study investigates the determinants of audit committee (AC) formation in a semi-mandatory setting of a European economy, in which ownership and control are predominantly in the hands of families and business groups, and the voluntary practice of forming an AC has not been widely accepted.

Methodology: This research uses a sample of Polish nonfinancial firms listed on the Warsaw Stock Exchange (WSE) in 2008–2015. The study implemented logistic regression to test the role of the supervisory board (SB) and companies’ compositional characteristics in AC creation.

Findings: Primary analysis provided evidence of an inverted association between commonly accepted determinants of AC formation – such as the number of independent members on the supervisory board (SB) – and accounting and finance expertise of the SB members. The study also revealed that companies with foreign ownership are more likely to have an AC.

Originality: This study indicates an important relationship between the existence of other SB committees as a meaningful determinant of AC formation. This article is valuable for supervisory bodies and regulators as they provide insights into factors that influence audit committee formation.