This study examines the associations of controlling shareholders and audit committee effectiveness with earnings quality. A sample of non-financial Thai listed firms is used in the study because Thailand provides a useful setting for the study of ownership concentration. A unique data set on the voting rights of controlling shareholders and audit committee characteristics is used to test the hypotheses of whether controlling shareholders and audit committees with strong governance characteristics affect the quality of earnings. Earnings quality is measured using (1) Basu's (1997) asymmetric timeliness measure of accounting conservatism, and (2) absolute abnormal accruals estimated from the Dechow and Dichev (2002) and the Jones (1991) models and its variations. Audit committee effectiveness is measured using a composite index comprising four audit committee characteristics.

 The empirical results show that firms with a controlling shareholder, on average, are associated with both lower accounting conservatism (lower earnings quality) and lower absolute abnormal accruals (higher earnings quality) than firms with no controlling shareholder.  Further analysis shows that family- and the government-controlled firms and firms whose controlling shareholders have voting rights below 75%, in particular, are associated with lower accounting conservatism and absolute abnormal accruals.  Although the results imply both lower and higher earnings quality for firms with a controlling shareholder compared to firms with no controlling shareholder, the lower (higher) absolute abnormal accruals (earnings quality) simply reflects less conservative accounting practice by firms with a controlling shareholder.  The results provide no evidence that audit committees with strong governance characteristics are associated with earnings quality.