家族企業之相關研究近來已成為學者關切的焦點，然文獻對於家族公司的定義相差頗大，因而研究結果相當紛歧。本研究利用家族公司在所有權、控制權及管理權三方面的特性，探討在不同的家族公司定義下，家族公司與非家族公司之盈餘品質差異；其次，我們也探討過去受到高度重視的兩種代理問題(管理階層與股東間的傳統代理問題，控制股東與小股東間的核心代理問題) 對於盈餘品質的交互作用影響。研究結果發現，相較於非家族企業，家族企業具有較差之盈餘品質。本研究也發現，當公司存在核心代理問題時，不論是否存在傳統代理問題，都會降低盈餘品質；相對的，公司經理人員是否由家族成員擔任，並不影響盈餘品質。然而，上述結論之成立係基於較嚴格之家族定義所得出之結果。 Since prior research found inconsistent conclusions for family firms under different family firm definitions, we incorporate three distinctive elements of family firms (ownership, management, and control) to begin our study with the question whether the earnings quality of family firms is different with that of nonfamily firms. The extant literature shows that there are two types of agency problem either arising from the classic owner-manager conflict or the conflict between family and nonfamily shareholders. In this paper, we further investigate the relative effects of these two agency problems on earnings quality. We find that family firms have more current accruals relative to nonfamily firms. Furthermore, the findings suggests that the earnings quality is lower when firms face the latter agency problem, either alone or joint with the former agency problem. Inconsistent with our prediction, our results show that the earnings quality would not be improved when family members serve as managers. However, our results hold only for more restrictive definitions of family firms.